HBASE-23935 : Backport HBASE-22978, HBASE-24528, HBASE-24718 to branch-1 (#2312)

* HBASE-22978: Online slow response log (with sub-tasks: Large logs, Replicate logs to HDFS, Filter support in query)
* HBASE-24718: Generic NamedQueue framework for recent in-memory history
* HBASE-24528: Improve balancer decision observability

Signed-off-by: Andrew Purtell <apurtell@apache.org>
Signed-off-by: Reid Chan <reidchan@apache.org>

hbase-client/src/main/java/org/apache/hadoop/hbase/client/Admin.java

@@ -22,6 +22,7 @@ import java.io.Closeable;
 import java.io.IOException;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.Future;
 import java.util.regex.Pattern;
 
@@ -1681,5 +1682,33 @@ public interface Admin extends Abortable, Closeable {
    */
   boolean isSnapshotCleanupEnabled() throws IOException;
 
+  /**
+   * Clears online slow/large RPC logs from the provided list of
+   * RegionServers
+   *
+   * @param serverNames Set of Server names to clean slowlog responses from
+   * @return List of booleans representing if online slowlog response buffer is cleaned
+   *   from each RegionServer
+   * @throws IOException if a remote or network exception occurs
+   */
+  List<Boolean> clearSlowLogResponses(final Set<ServerName> serverNames)
+    throws IOException;
 
+
+  /**
+   * Retrieve recent online records from HMaster / RegionServers.
+   * Examples include slow/large RPC logs, balancer decisions by master.
+   *
+   * @param serverNames servers to retrieve records from, useful in case of records maintained
+   *   by RegionServer as we can select specific server. In case of servertype=MASTER, logs will
+   *   only come from the currently active master.
+   * @param logType string representing type of log records
+   * @param serverType enum for server type: HMaster or RegionServer
+   * @param limit put a limit to list of records that server should send in response
+   * @param filterParams additional filter params
+   * @return Log entries representing online records from servers
+   * @throws IOException if a remote or network exception occurs
+   */
+  List<LogEntry> getLogEntries(Set<ServerName> serverNames, String logType,
+    ServerType serverType, int limit, Map<String, Object> filterParams) throws IOException;
 }

hbase-client/src/main/java/org/apache/hadoop/hbase/client/BalancerDecision.java

@@ -0,0 +1,160 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.client;
+
+import java.lang.reflect.Type;
+import java.util.List;
+
+import org.apache.commons.lang.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.classification.InterfaceStability;
+import org.apache.hadoop.hbase.util.GsonUtil;
+
+import org.apache.hbase.thirdparty.com.google.gson.Gson;
+import org.apache.hbase.thirdparty.com.google.gson.JsonElement;
+import org.apache.hbase.thirdparty.com.google.gson.JsonSerializationContext;
+import org.apache.hbase.thirdparty.com.google.gson.JsonSerializer;
+
+/**
+ * History of balancer decisions taken for region movements.
+ */
+@InterfaceAudience.Public
+@InterfaceStability.Evolving
+final public class BalancerDecision extends LogEntry {
+
+  private final String initialFunctionCosts;
+  private final String finalFunctionCosts;
+  private final double initTotalCost;
+  private final double computedTotalCost;
+  private final long computedSteps;
+  private final List<String> regionPlans;
+
+  // used to convert object to pretty printed format
+  // used by toJsonPrettyPrint()
+  private static final Gson GSON = GsonUtil.createGson()
+    .setPrettyPrinting()
+    .registerTypeAdapter(BalancerDecision.class, new JsonSerializer<BalancerDecision>() {
+      @Override
+      public JsonElement serialize(BalancerDecision balancerDecision, Type type,
+        JsonSerializationContext jsonSerializationContext) {
+        Gson gson = new Gson();
+        return gson.toJsonTree(balancerDecision);
+      }
+    }).create();
+
+  private BalancerDecision(String initialFunctionCosts, String finalFunctionCosts,
+    double initTotalCost, double computedTotalCost, List<String> regionPlans,
+    long computedSteps) {
+    this.initialFunctionCosts = initialFunctionCosts;
+    this.finalFunctionCosts = finalFunctionCosts;
+    this.initTotalCost = initTotalCost;
+    this.computedTotalCost = computedTotalCost;
+    this.regionPlans = regionPlans;
+    this.computedSteps = computedSteps;
+  }
+
+  public String getInitialFunctionCosts() {
+    return initialFunctionCosts;
+  }
+
+  public String getFinalFunctionCosts() {
+    return finalFunctionCosts;
+  }
+
+  public double getInitTotalCost() {
+    return initTotalCost;
+  }
+
+  public double getComputedTotalCost() {
+    return computedTotalCost;
+  }
+
+  public List<String> getRegionPlans() {
+    return regionPlans;
+  }
+
+  public long getComputedSteps() {
+    return computedSteps;
+  }
+
+  @Override
+  public String toString() {
+    return new ToStringBuilder(this)
+      .append("initialFunctionCosts", initialFunctionCosts)
+      .append("finalFunctionCosts", finalFunctionCosts)
+      .append("initTotalCost", initTotalCost)
+      .append("computedTotalCost", computedTotalCost)
+      .append("computedSteps", computedSteps)
+      .append("regionPlans", regionPlans)
+      .toString();
+  }
+
+  @Override
+  public String toJsonPrettyPrint() {
+    return GSON.toJson(this);
+  }
+
+  @InterfaceAudience.Public
+  @InterfaceStability.Evolving
+  public static class Builder {
+    private String initialFunctionCosts;
+    private String finalFunctionCosts;
+    private double initTotalCost;
+    private double computedTotalCost;
+    private long computedSteps;
+    private List<String> regionPlans;
+
+    public Builder setInitialFunctionCosts(String initialFunctionCosts) {
+      this.initialFunctionCosts = initialFunctionCosts;
+      return this;
+    }
+
+    public Builder setFinalFunctionCosts(String finalFunctionCosts) {
+      this.finalFunctionCosts = finalFunctionCosts;
+      return this;
+    }
+
+    public Builder setInitTotalCost(double initTotalCost) {
+      this.initTotalCost = initTotalCost;
+      return this;
+    }
+
+    public Builder setComputedTotalCost(double computedTotalCost) {
+      this.computedTotalCost = computedTotalCost;
+      return this;
+    }
+
+    public Builder setRegionPlans(List<String> regionPlans) {
+      this.regionPlans = regionPlans;
+      return this;
+    }
+
+    public Builder setComputedSteps(long computedSteps) {
+      this.computedSteps = computedSteps;
+      return this;
+    }
+
+    public BalancerDecision build() {
+      return new BalancerDecision(initialFunctionCosts, finalFunctionCosts,
+        initTotalCost, computedTotalCost, regionPlans, computedSteps);
+    }
+  }
+
+}

hbase-client/src/main/java/org/apache/hadoop/hbase/client/ConnectionManager.java

@@ -83,6 +83,7 @@ import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService;
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ClientService;
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.CoprocessorServiceRequest;
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.CoprocessorServiceResponse;
+import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
 import org.apache.hadoop.hbase.protobuf.generated.MasterProtos;
 import org.apache.hadoop.hbase.protobuf.generated.MasterProtos.AddColumnRequest;
 import org.apache.hadoop.hbase.protobuf.generated.MasterProtos.AddColumnResponse;
@@ -2145,6 +2146,12 @@ class ConnectionManager {
           return stub.isSnapshotCleanupEnabled(controller, request);
         }
 
+        @Override
+        public HBaseProtos.LogEntry getLogEntries(RpcController controller,
+            HBaseProtos.LogRequest request) throws ServiceException {
+          return stub.getLogEntries(controller, request);
+        }
+
         @Override
         public ListNamespaceDescriptorsResponse listNamespaceDescriptors(RpcController controller,
             ListNamespaceDescriptorsRequest request) throws ServiceException {

hbase-client/src/main/java/org/apache/hadoop/hbase/client/HBaseAdmin.java

@@ -26,11 +26,13 @@ import java.io.IOException;
 import java.io.InterruptedIOException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Set;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
@@ -79,6 +81,7 @@ import org.apache.hadoop.hbase.ipc.RegionServerCoprocessorRpcChannel;
 import org.apache.hadoop.hbase.ipc.RpcControllerFactory;
 import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
 import org.apache.hadoop.hbase.protobuf.RequestConverter;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.CloseRegionRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.CloseRegionResponse;
@@ -175,6 +178,7 @@ import org.apache.hadoop.hbase.snapshot.SnapshotCreationException;
 import org.apache.hadoop.hbase.snapshot.UnknownSnapshotException;
 import org.apache.hadoop.hbase.util.Addressing;
 import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.CollectionUtils;
 import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
 import org.apache.hadoop.hbase.util.ForeignExceptionUtil;
 import org.apache.hadoop.hbase.util.Pair;
@@ -5089,4 +5093,92 @@ public class HBaseAdmin implements Admin {
 
   }
 
+  private List<LogEntry> getSlowLogResponses(
+      final Map<String, Object> filterParams, final Set<ServerName> serverNames, final int limit,
+      final String logType) {
+    if (CollectionUtils.isEmpty(serverNames)) {
+      return Collections.emptyList();
+    }
+    List<LogEntry> logRecords = new ArrayList<>();
+    for (ServerName serverName : serverNames) {
+      try {
+        logRecords.addAll(getSlowLogs(serverName, filterParams, limit, logType));
+      } catch (ServiceException | IOException e) {
+        throw new RuntimeException(e);
+      }
+    }
+    return logRecords;
+  }
+
+  private List<LogEntry> getSlowLogs(ServerName serverName, Map<String, Object> filterParams,
+      int limit, String logType) throws IOException, ServiceException {
+    AdminService.BlockingInterface admin = this.connection.getAdmin(serverName);
+    HBaseRpcController controller = rpcControllerFactory.newController();
+    HBaseProtos.LogRequest logRequest =
+      RequestConverter.buildSlowLogResponseRequest(filterParams, limit, logType);
+    HBaseProtos.LogEntry logEntry = admin.getLogEntries(controller, logRequest);
+    return ProtobufUtil.toSlowLogPayloads(logEntry);
+  }
+
+  @Override
+  public List<Boolean> clearSlowLogResponses(Set<ServerName> serverNames)
+    throws IOException {
+    if (CollectionUtils.isEmpty(serverNames)) {
+      return Collections.emptyList();
+    }
+    List<Boolean> logsCleared = new ArrayList<>();
+    for (ServerName serverName : serverNames) {
+      try {
+        logsCleared.add(clearSlowLogsResponses(serverName));
+      } catch (ServiceException e) {
+        throw new RuntimeException(e);
+      }
+    }
+    return logsCleared;
+  }
+
+  private Boolean clearSlowLogsResponses(final ServerName serverName)
+      throws IOException, ServiceException {
+    AdminService.BlockingInterface admin = this.connection.getAdmin(serverName);
+    HBaseRpcController controller = rpcControllerFactory.newController();
+    AdminProtos.ClearSlowLogResponses clearSlowLogResponses =
+      admin.clearSlowLogsResponses(controller,
+        RequestConverter.buildClearSlowLogResponseRequest());
+    return ProtobufUtil.toClearSlowLogPayload(clearSlowLogResponses);
+  }
+
+  @Override
+  public List<LogEntry> getLogEntries(Set<ServerName> serverNames, String logType,
+    ServerType serverType, int limit, Map<String, Object> filterParams) throws IOException {
+    if (logType == null || serverType == null) {
+      throw new IllegalArgumentException("logType and/or serverType cannot be empty");
+    }
+    if (logType.equals("SLOW_LOG") || logType.equals("LARGE_LOG")) {
+      if (ServerType.MASTER.equals(serverType)) {
+        throw new IllegalArgumentException("Slow/Large logs are not maintained by HMaster");
+      }
+      return getSlowLogResponses(filterParams, serverNames, limit, logType);
+    } else if (logType.equals("BALANCER_DECISION")) {
+      if (ServerType.REGION_SERVER.equals(serverType)) {
+        throw new IllegalArgumentException(
+          "Balancer Decision logs are not maintained by HRegionServer");
+      }
+      return getBalancerDecisions(limit);
+    }
+    return Collections.emptyList();
+  }
+
+  private List<LogEntry> getBalancerDecisions(final int limit) throws IOException {
+    return executeCallable(new MasterCallable<List<LogEntry>>(getConnection()) {
+      @Override
+      public List<LogEntry> call(int callTimeout) throws Exception {
+        HBaseRpcController controller = rpcControllerFactory.newController();
+        controller.setCallTimeout(callTimeout);
+        HBaseProtos.LogEntry logEntry =
+          master.getLogEntries(controller, ProtobufUtil.toBalancerDecisionRequest(limit));
+        return ProtobufUtil.toBalancerDecisionResponse(logEntry);
+      }
+    });
+  }
+
 }

hbase-client/src/main/java/org/apache/hadoop/hbase/client/LogEntry.java

@@ -0,0 +1,39 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.client;
+
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.classification.InterfaceStability;
+
+/**
+ * Abstract response class representing online logs response from ring-buffer use-cases
+ * e.g slow/large RPC logs, balancer decision logs
+ */
+@InterfaceAudience.Public
+@InterfaceStability.Evolving
+public abstract class LogEntry {
+
+  /**
+   * Based on response sent by server, provide pretty printed Json representation in string
+   * @return Pretty printed Json representation
+   */
+  public abstract String toJsonPrettyPrint();
+
+}

hbase-client/src/main/java/org/apache/hadoop/hbase/client/OnlineLogRecord.java

@@ -0,0 +1,329 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.client;
+
+import java.lang.reflect.Type;
+
+import org.apache.commons.lang.builder.EqualsBuilder;
+import org.apache.commons.lang.builder.HashCodeBuilder;
+import org.apache.commons.lang.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.classification.InterfaceStability;
+import org.apache.hadoop.hbase.util.GsonUtil;
+
+import org.apache.hbase.thirdparty.com.google.gson.Gson;
+import org.apache.hbase.thirdparty.com.google.gson.JsonElement;
+import org.apache.hbase.thirdparty.com.google.gson.JsonObject;
+import org.apache.hbase.thirdparty.com.google.gson.JsonSerializationContext;
+import org.apache.hbase.thirdparty.com.google.gson.JsonSerializer;
+
+/**
+ * Slow/Large Log payload for hbase-client, to be used by Admin API get_slow_responses and
+ * get_large_responses
+ */
+@InterfaceAudience.Public
+@InterfaceStability.Evolving
+final public class OnlineLogRecord extends LogEntry {
+  // used to convert object to pretty printed format
+  // used by toJsonPrettyPrint()
+  private static final Gson GSON = GsonUtil.createGson().setPrettyPrinting()
+    .registerTypeAdapter(OnlineLogRecord.class, new JsonSerializer<OnlineLogRecord>() {
+      @Override
+      public JsonElement serialize(OnlineLogRecord slowLogPayload, Type type,
+        JsonSerializationContext jsonSerializationContext) {
+        Gson gson = new Gson();
+        JsonObject jsonObj = (JsonObject) gson.toJsonTree(slowLogPayload);
+        if (slowLogPayload.getMultiGetsCount() == 0) {
+          jsonObj.remove("multiGetsCount");
+        }
+        if (slowLogPayload.getMultiMutationsCount() == 0) {
+          jsonObj.remove("multiMutationsCount");
+        }
+        if (slowLogPayload.getMultiServiceCalls() == 0) {
+          jsonObj.remove("multiServiceCalls");
+        }
+        return jsonObj;
+      }
+    }).create();
+
+  private final long startTime;
+  private final int processingTime;
+  private final int queueTime;
+  private final long responseSize;
+  private final String clientAddress;
+  private final String serverClass;
+  private final String methodName;
+  private final String callDetails;
+  private final String param;
+  // we don't want to serialize region name, it is just for the filter purpose
+  // hence avoiding deserialization
+  private final transient String regionName;
+  private final String userName;
+  private final int multiGetsCount;
+  private final int multiMutationsCount;
+  private final int multiServiceCalls;
+
+  public long getStartTime() {
+    return startTime;
+  }
+
+  public int getProcessingTime() {
+    return processingTime;
+  }
+
+  public int getQueueTime() {
+    return queueTime;
+  }
+
+  public long getResponseSize() {
+    return responseSize;
+  }
+
+  public String getClientAddress() {
+    return clientAddress;
+  }
+
+  public String getServerClass() {
+    return serverClass;
+  }
+
+  public String getMethodName() {
+    return methodName;
+  }
+
+  public String getCallDetails() {
+    return callDetails;
+  }
+
+  public String getParam() {
+    return param;
+  }
+
+  public String getRegionName() {
+    return regionName;
+  }
+
+  public String getUserName() {
+    return userName;
+  }
+
+  public int getMultiGetsCount() {
+    return multiGetsCount;
+  }
+
+  public int getMultiMutationsCount() {
+    return multiMutationsCount;
+  }
+
+  public int getMultiServiceCalls() {
+    return multiServiceCalls;
+  }
+
+  private OnlineLogRecord(final long startTime, final int processingTime, final int queueTime,
+    final long responseSize, final String clientAddress, final String serverClass,
+    final String methodName, final String callDetails, final String param,
+    final String regionName, final String userName, final int multiGetsCount,
+    final int multiMutationsCount, final int multiServiceCalls) {
+    this.startTime = startTime;
+    this.processingTime = processingTime;
+    this.queueTime = queueTime;
+    this.responseSize = responseSize;
+    this.clientAddress = clientAddress;
+    this.serverClass = serverClass;
+    this.methodName = methodName;
+    this.callDetails = callDetails;
+    this.param = param;
+    this.regionName = regionName;
+    this.userName = userName;
+    this.multiGetsCount = multiGetsCount;
+    this.multiMutationsCount = multiMutationsCount;
+    this.multiServiceCalls = multiServiceCalls;
+  }
+
+  @InterfaceAudience.Public
+  @InterfaceStability.Evolving
+  public static class OnlineLogRecordBuilder {
+    private long startTime;
+    private int processingTime;
+    private int queueTime;
+    private long responseSize;
+    private String clientAddress;
+    private String serverClass;
+    private String methodName;
+    private String callDetails;
+    private String param;
+    private String regionName;
+    private String userName;
+    private int multiGetsCount;
+    private int multiMutationsCount;
+    private int multiServiceCalls;
+
+    public OnlineLogRecordBuilder setStartTime(long startTime) {
+      this.startTime = startTime;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setProcessingTime(int processingTime) {
+      this.processingTime = processingTime;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setQueueTime(int queueTime) {
+      this.queueTime = queueTime;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setResponseSize(long responseSize) {
+      this.responseSize = responseSize;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setClientAddress(String clientAddress) {
+      this.clientAddress = clientAddress;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setServerClass(String serverClass) {
+      this.serverClass = serverClass;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setMethodName(String methodName) {
+      this.methodName = methodName;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setCallDetails(String callDetails) {
+      this.callDetails = callDetails;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setParam(String param) {
+      this.param = param;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setRegionName(String regionName) {
+      this.regionName = regionName;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setUserName(String userName) {
+      this.userName = userName;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setMultiGetsCount(int multiGetsCount) {
+      this.multiGetsCount = multiGetsCount;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setMultiMutationsCount(int multiMutationsCount) {
+      this.multiMutationsCount = multiMutationsCount;
+      return this;
+    }
+
+    public OnlineLogRecordBuilder setMultiServiceCalls(int multiServiceCalls) {
+      this.multiServiceCalls = multiServiceCalls;
+      return this;
+    }
+
+    public OnlineLogRecord build() {
+      return new OnlineLogRecord(startTime, processingTime, queueTime, responseSize,
+        clientAddress, serverClass, methodName, callDetails, param, regionName,
+        userName, multiGetsCount, multiMutationsCount, multiServiceCalls);
+    }
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+
+    OnlineLogRecord that = (OnlineLogRecord) o;
+
+    return new EqualsBuilder()
+      .append(startTime, that.startTime)
+      .append(processingTime, that.processingTime)
+      .append(queueTime, that.queueTime)
+      .append(responseSize, that.responseSize)
+      .append(multiGetsCount, that.multiGetsCount)
+      .append(multiMutationsCount, that.multiMutationsCount)
+      .append(multiServiceCalls, that.multiServiceCalls)
+      .append(clientAddress, that.clientAddress)
+      .append(serverClass, that.serverClass)
+      .append(methodName, that.methodName)
+      .append(callDetails, that.callDetails)
+      .append(param, that.param)
+      .append(regionName, that.regionName)
+      .append(userName, that.userName)
+      .isEquals();
+  }
+
+  @Override
+  public int hashCode() {
+    return new HashCodeBuilder(17, 37)
+      .append(startTime)
+      .append(processingTime)
+      .append(queueTime)
+      .append(responseSize)
+      .append(clientAddress)
+      .append(serverClass)
+      .append(methodName)
+      .append(callDetails)
+      .append(param)
+      .append(regionName)
+      .append(userName)
+      .append(multiGetsCount)
+      .append(multiMutationsCount)
+      .append(multiServiceCalls)
+      .toHashCode();
+  }
+
+  public String toJsonPrettyPrint() {
+    return GSON.toJson(this);
+  }
+
+  @Override
+  public String toString() {
+    return new ToStringBuilder(this)
+      .append("startTime", startTime)
+      .append("processingTime", processingTime)
+      .append("queueTime", queueTime)
+      .append("responseSize", responseSize)
+      .append("clientAddress", clientAddress)
+      .append("serverClass", serverClass)
+      .append("methodName", methodName)
+      .append("callDetails", callDetails)
+      .append("param", param)
+      .append("regionName", regionName)
+      .append("userName", userName)
+      .append("multiGetsCount", multiGetsCount)
+      .append("multiMutationsCount", multiMutationsCount)
+      .append("multiServiceCalls", multiServiceCalls)
+      .toString();
+  }
+
+}

hbase-client/src/main/java/org/apache/hadoop/hbase/client/ServerType.java

@@ -0,0 +1,35 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.client;
+
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.classification.InterfaceStability;
+
+/**
+ * Select server type i.e destination for RPC request associated with ring buffer.
+ * e.g slow/large log records are maintained by HRegionServer, whereas balancer decisions
+ * are maintained by HMaster.
+ */
+@InterfaceAudience.Public
+@InterfaceStability.Stable
+public enum ServerType {
+  MASTER,
+  REGION_SERVER
+}

hbase-client/src/main/java/org/apache/hadoop/hbase/client/SlowLogParams.java

@@ -0,0 +1,89 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.client;
+
+import org.apache.commons.lang.StringUtils;
+import org.apache.commons.lang.builder.EqualsBuilder;
+import org.apache.commons.lang.builder.HashCodeBuilder;
+import org.apache.commons.lang.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+
+/**
+ * SlowLog params object that contains detailed info as params and region name : to be used
+ * for filter purpose
+ */
+@InterfaceAudience.Private
+public class SlowLogParams {
+
+  private final String regionName;
+  private final String params;
+
+  public SlowLogParams(String regionName, String params) {
+    this.regionName = regionName;
+    this.params = params;
+  }
+
+  public SlowLogParams(String params) {
+    this.regionName = StringUtils.EMPTY;
+    this.params = params;
+  }
+
+  public String getRegionName() {
+    return regionName;
+  }
+
+  public String getParams() {
+    return params;
+  }
+
+  @Override
+  public String toString() {
+    return new ToStringBuilder(this)
+      .append("regionName", regionName)
+      .append("params", params)
+      .toString();
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+
+    SlowLogParams that = (SlowLogParams) o;
+
+    return new EqualsBuilder()
+      .append(regionName, that.regionName)
+      .append(params, that.params)
+      .isEquals();
+  }
+
+  @Override
+  public int hashCode() {
+    return new HashCodeBuilder(17, 37)
+      .append(regionName)
+      .append(params)
+      .toHashCode();
+  }
+}

hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/ProtobufUtil.java

@@ -77,6 +77,7 @@ import org.apache.hadoop.hbase.TableName;
 import org.apache.hadoop.hbase.Tag;
 import org.apache.hadoop.hbase.classification.InterfaceAudience;
 import org.apache.hadoop.hbase.client.Append;
+import org.apache.hadoop.hbase.client.BalancerDecision;
 import org.apache.hadoop.hbase.client.ClientUtil;
 import org.apache.hadoop.hbase.client.Consistency;
 import org.apache.hadoop.hbase.client.Cursor;
@@ -84,12 +85,15 @@ import org.apache.hadoop.hbase.client.Delete;
 import org.apache.hadoop.hbase.client.Durability;
 import org.apache.hadoop.hbase.client.Get;
 import org.apache.hadoop.hbase.client.Increment;
+import org.apache.hadoop.hbase.client.LogEntry;
 import org.apache.hadoop.hbase.client.Mutation;
+import org.apache.hadoop.hbase.client.OnlineLogRecord;
 import org.apache.hadoop.hbase.client.PackagePrivateFieldAccessor;
 import org.apache.hadoop.hbase.client.Put;
 import org.apache.hadoop.hbase.client.RegionReplicaUtil;
 import org.apache.hadoop.hbase.client.Result;
 import org.apache.hadoop.hbase.client.Scan;
+import org.apache.hadoop.hbase.client.SlowLogParams;
 import org.apache.hadoop.hbase.client.metrics.ScanMetrics;
 import org.apache.hadoop.hbase.client.security.SecurityCapability;
 import org.apache.hadoop.hbase.exceptions.DeserializationException;
@@ -101,6 +105,7 @@ import org.apache.hadoop.hbase.master.RegionState;
 import org.apache.hadoop.hbase.protobuf.generated.AccessControlProtos;
 import org.apache.hadoop.hbase.protobuf.generated.AccessControlProtos.AccessControlService;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.ClearSlowLogResponses;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.CloseRegionRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.CloseRegionResponse;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.GetOnlineRegionRequest;
@@ -114,6 +119,7 @@ import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.GetStoreFileRespon
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.MergeRegionsRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.OpenRegionRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.ServerInfo;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.SlowLogResponses;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.SplitRegionRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.WarmupRegionRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AuthenticationProtos;
@@ -150,9 +156,11 @@ import org.apache.hadoop.hbase.protobuf.generated.MasterProtos.CreateTableReques
 import org.apache.hadoop.hbase.protobuf.generated.MasterProtos.GetTableDescriptorsResponse;
 import org.apache.hadoop.hbase.protobuf.generated.MasterProtos.MasterService;
 import org.apache.hadoop.hbase.protobuf.generated.QuotaProtos;
+import org.apache.hadoop.hbase.protobuf.generated.RecentLogs;
 import org.apache.hadoop.hbase.protobuf.generated.RegionServerStatusProtos.RegionServerReportRequest;
 import org.apache.hadoop.hbase.protobuf.generated.RegionServerStatusProtos.RegionServerStartupRequest;
 import org.apache.hadoop.hbase.protobuf.generated.TableProtos;
+import org.apache.hadoop.hbase.protobuf.generated.TooSlowLog;
 import org.apache.hadoop.hbase.protobuf.generated.WALProtos;
 import org.apache.hadoop.hbase.protobuf.generated.WALProtos.BulkLoadDescriptor;
 import org.apache.hadoop.hbase.protobuf.generated.WALProtos.CompactionDescriptor;
@@ -177,6 +185,7 @@ import org.apache.hadoop.hbase.security.visibility.CellVisibility;
 import org.apache.hadoop.hbase.util.Addressing;
 import org.apache.hadoop.hbase.util.ByteStringer;
 import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.CollectionUtils;
 import org.apache.hadoop.hbase.util.DynamicClassLoader;
 import org.apache.hadoop.hbase.util.ExceptionUtil;
 import org.apache.hadoop.hbase.util.Methods;
@@ -3034,6 +3043,62 @@ public final class ProtobufUtil {
     return Bytes.toStringBinary(bs.toByteArray());
   }
 
+  /**
+   * Return SlowLogParams to maintain recent online slowlog responses
+   *
+   * @param message Message object {@link Message}
+   * @return SlowLogParams with regionName(for filter queries) and params
+   */
+  public static SlowLogParams getSlowLogParams(Message message) {
+    if (message == null) {
+      return null;
+    }
+    if (message instanceof ScanRequest) {
+      ScanRequest scanRequest = (ScanRequest) message;
+      String regionName = getStringForByteString(scanRequest.getRegion().getValue());
+      String params = TextFormat.shortDebugString(message);
+      return new SlowLogParams(regionName, params);
+    } else if (message instanceof MutationProto) {
+      MutationProto mutationProto = (MutationProto) message;
+      String params = "type= " + mutationProto.getMutateType().toString();
+      return new SlowLogParams(params);
+    } else if (message instanceof GetRequest) {
+      GetRequest getRequest = (GetRequest) message;
+      String regionName = getStringForByteString(getRequest.getRegion().getValue());
+      String params =
+        "region= " + regionName + ", row= " + getStringForByteString(getRequest.getGet().getRow());
+      return new SlowLogParams(regionName, params);
+    } else if (message instanceof ClientProtos.MultiRequest) {
+      ClientProtos.MultiRequest multiRequest = (ClientProtos.MultiRequest) message;
+      int actionsCount = 0;
+      for (ClientProtos.RegionAction regionAction : multiRequest.getRegionActionList()) {
+        actionsCount += regionAction.getActionCount();
+      }
+      ClientProtos.RegionAction actions = multiRequest.getRegionActionList().get(0);
+      String row = actions.getActionCount() <= 0 ? "" :
+        getStringForByteString(actions.getAction(0).hasGet() ?
+          actions.getAction(0).getGet().getRow() :
+          actions.getAction(0).getMutation().getRow());
+      String regionName = getStringForByteString(actions.getRegion().getValue());
+      String params =
+        "region= " + regionName + ", for " + actionsCount + " action(s) and 1st row key=" + row;
+      return new SlowLogParams(regionName, params);
+    } else if (message instanceof ClientProtos.MutateRequest) {
+      ClientProtos.MutateRequest mutateRequest = (ClientProtos.MutateRequest) message;
+      String regionName = getStringForByteString(mutateRequest.getRegion().getValue());
+      String params = "region= " + regionName;
+      return new SlowLogParams(regionName, params);
+    } else if (message instanceof CoprocessorServiceRequest) {
+      CoprocessorServiceRequest coprocessorServiceRequest = (CoprocessorServiceRequest) message;
+      String params =
+        "coprocessorService= " + coprocessorServiceRequest.getCall().getServiceName() + ":"
+          + coprocessorServiceRequest.getCall().getMethodName();
+      return new SlowLogParams(params);
+    }
+    String params = message.getClass().toString();
+    return new SlowLogParams(params);
+  }
+
   /**
    * Print out some subset of a MutationProto rather than all of it and its data
    * @param proto Protobuf to print out
@@ -3663,6 +3728,121 @@ public final class ProtobufUtil {
     return Collections.emptySet();
   }
 
+  /**
+   * Convert Protobuf class
+   * {@link TooSlowLog.SlowLogPayload}
+   * To client SlowLog Payload class {@link OnlineLogRecord}
+   *
+   * @param slowLogPayload SlowLog Payload protobuf instance
+   * @return SlowLog Payload for client usecase
+   */
+  private static LogEntry getSlowLogRecord(
+      final TooSlowLog.SlowLogPayload slowLogPayload) {
+    OnlineLogRecord onlineLogRecord = new OnlineLogRecord.OnlineLogRecordBuilder()
+      .setCallDetails(slowLogPayload.getCallDetails())
+      .setClientAddress(slowLogPayload.getClientAddress())
+      .setMethodName(slowLogPayload.getMethodName())
+      .setMultiGetsCount(slowLogPayload.getMultiGets())
+      .setMultiMutationsCount(slowLogPayload.getMultiMutations())
+      .setMultiServiceCalls(slowLogPayload.getMultiServiceCalls())
+      .setParam(slowLogPayload.getParam())
+      .setProcessingTime(slowLogPayload.getProcessingTime())
+      .setQueueTime(slowLogPayload.getQueueTime())
+      .setRegionName(slowLogPayload.getRegionName())
+      .setResponseSize(slowLogPayload.getResponseSize())
+      .setServerClass(slowLogPayload.getServerClass())
+      .setStartTime(slowLogPayload.getStartTime())
+      .setUserName(slowLogPayload.getUserName())
+      .build();
+    return onlineLogRecord;
+  }
+
+  /**
+   * Convert  AdminProtos#SlowLogResponses to list of {@link OnlineLogRecord}
+   *
+   * @param logEntry slowlog response protobuf instance
+   * @return list of SlowLog payloads for client usecase
+   */
+  public static List<LogEntry> toSlowLogPayloads(
+      final HBaseProtos.LogEntry logEntry) {
+    try {
+      final String logClassName = logEntry.getLogClassName();
+      Class<?> logClass = Class.forName(logClassName).asSubclass(Message.class);
+      Method method = logClass.getMethod("parseFrom", ByteString.class);
+      if (logClassName.contains("SlowLogResponses")) {
+        SlowLogResponses slowLogResponses = (SlowLogResponses) method
+          .invoke(null, logEntry.getLogMessage());
+        List<LogEntry> logEntries = new ArrayList<>();
+        for (TooSlowLog.SlowLogPayload slowLogPayload : slowLogResponses.getSlowLogPayloadsList()) {
+          logEntries.add(ProtobufUtil.getSlowLogRecord(slowLogPayload));
+        }
+        return logEntries;
+      }
+    } catch (ClassNotFoundException | NoSuchMethodException | IllegalAccessException
+      | InvocationTargetException e) {
+      throw new RuntimeException("Error while retrieving response from server");
+    }
+    throw new RuntimeException("Invalid response from server");
+  }
+
+  /**
+   * Convert {@link ClearSlowLogResponses} to boolean
+   *
+   * @param clearSlowLogResponses Clear slowlog response protobuf instance
+   * @return boolean representing clear slowlog response
+   */
+  public static boolean toClearSlowLogPayload(final ClearSlowLogResponses clearSlowLogResponses) {
+    return clearSlowLogResponses.getIsCleaned();
+  }
+
+  public static List<LogEntry> toBalancerDecisionResponse(
+      HBaseProtos.LogEntry logEntry) {
+    try {
+      final String logClassName = logEntry.getLogClassName();
+      Class<?> logClass = Class.forName(logClassName).asSubclass(Message.class);
+      Method method = logClass.getMethod("parseFrom", ByteString.class);
+      if (logClassName.contains("BalancerDecisionsResponse")) {
+        MasterProtos.BalancerDecisionsResponse response =
+          (MasterProtos.BalancerDecisionsResponse) method
+            .invoke(null, logEntry.getLogMessage());
+        return getBalancerDecisionEntries(response);
+      }
+    } catch (ClassNotFoundException | NoSuchMethodException | IllegalAccessException
+      | InvocationTargetException e) {
+      throw new RuntimeException("Error while retrieving response from server");
+    }
+    throw new RuntimeException("Invalid response from server");
+  }
+
+  public static List<LogEntry> getBalancerDecisionEntries(
+      MasterProtos.BalancerDecisionsResponse response) {
+    List<RecentLogs.BalancerDecision> balancerDecisions = response.getBalancerDecisionList();
+    if (CollectionUtils.isEmpty(balancerDecisions)) {
+      return Collections.emptyList();
+    }
+    List<LogEntry> logEntries = new ArrayList<>();
+    for (RecentLogs.BalancerDecision balancerDecision : balancerDecisions) {
+      BalancerDecision bd =
+        new BalancerDecision.Builder().setInitTotalCost(balancerDecision.getInitTotalCost())
+          .setInitialFunctionCosts(balancerDecision.getInitialFunctionCosts())
+          .setComputedTotalCost(balancerDecision.getComputedTotalCost())
+          .setFinalFunctionCosts(balancerDecision.getFinalFunctionCosts())
+          .setComputedSteps(balancerDecision.getComputedSteps())
+          .setRegionPlans(balancerDecision.getRegionPlansList()).build();
+      logEntries.add(bd);
+    }
+    return logEntries;
+  }
+
+  public static HBaseProtos.LogRequest toBalancerDecisionRequest(int limit) {
+    MasterProtos.BalancerDecisionsRequest balancerDecisionsRequest =
+      MasterProtos.BalancerDecisionsRequest.newBuilder().setLimit(limit).build();
+    return HBaseProtos.LogRequest.newBuilder()
+      .setLogClassName(balancerDecisionsRequest.getClass().getName())
+      .setLogMessage(balancerDecisionsRequest.toByteString())
+      .build();
+  }
+
   /**
    * Get the Meta region state from the passed data bytes. Can handle both old and new style
    * server names.

hbase-client/src/main/java/org/apache/hadoop/hbase/protobuf/RequestConverter.java

@@ -19,8 +19,11 @@ package org.apache.hadoop.hbase.protobuf;
 
 import java.io.IOException;
 import java.util.List;
+import java.util.Map;
 import java.util.regex.Pattern;
 
+import org.apache.commons.collections.MapUtils;
+import org.apache.commons.lang.StringUtils;
 import org.apache.hadoop.hbase.classification.InterfaceAudience;
 import org.apache.hadoop.hbase.util.ByteStringer;
 
@@ -48,6 +51,7 @@ import org.apache.hadoop.hbase.client.Scan;
 import org.apache.hadoop.hbase.exceptions.DeserializationException;
 import org.apache.hadoop.hbase.filter.ByteArrayComparable;
 import org.apache.hadoop.hbase.protobuf.generated.AccessControlProtos;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.ClearSlowLogResponseRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.CloseRegionRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.CompactRegionRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.FlushRegionRequest;
@@ -59,6 +63,7 @@ import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.MergeRegionsReques
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.OpenRegionRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.OpenRegionRequest.RegionOpenInfo;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.RollWALWriterRequest;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.SlowLogResponseRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.SplitRegionRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.StopServerRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.UpdateFavoredNodesRequest;
@@ -77,6 +82,7 @@ import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.MutationProto.Col
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.MutationProto.MutationType;
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.RegionAction;
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ScanRequest;
+import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
 import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.CompareType;
 import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.RegionSpecifier;
 import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.RegionSpecifier.RegionSpecifierType;
@@ -1895,4 +1901,77 @@ public final class RequestConverter {
     return IsSnapshotCleanupEnabledRequest.newBuilder().build();
   }
 
+  /**
+   * Build RPC request payload for getLogEntries
+   *
+   * @param filterParams map of filter params
+   * @param limit limit for no of records that server returns
+   * @param logType type of the log records
+   * @return request payload HBaseProtos.LogRequest
+   */
+  public static HBaseProtos.LogRequest buildSlowLogResponseRequest(
+      final Map<String, Object> filterParams, final int limit, final String logType) {
+    SlowLogResponseRequest.Builder builder = SlowLogResponseRequest.newBuilder();
+    builder.setLimit(limit);
+    if (logType.equals("SLOW_LOG")) {
+      builder.setLogType(SlowLogResponseRequest.LogType.SLOW_LOG);
+    } else if (logType.equals("LARGE_LOG")) {
+      builder.setLogType(SlowLogResponseRequest.LogType.LARGE_LOG);
+    }
+    boolean filterByAnd = false;
+    if (MapUtils.isNotEmpty(filterParams)) {
+      if (filterParams.containsKey("clientAddress")) {
+        final String clientAddress = (String) filterParams.get("clientAddress");
+        if (StringUtils.isNotEmpty(clientAddress)) {
+          builder.setClientAddress(clientAddress);
+        }
+      }
+      if (filterParams.containsKey("regionName")) {
+        final String regionName = (String) filterParams.get("regionName");
+        if (StringUtils.isNotEmpty(regionName)) {
+          builder.setRegionName(regionName);
+        }
+      }
+      if (filterParams.containsKey("tableName")) {
+        final String tableName = (String) filterParams.get("tableName");
+        if (StringUtils.isNotEmpty(tableName)) {
+          builder.setTableName(tableName);
+        }
+      }
+      if (filterParams.containsKey("userName")) {
+        final String userName = (String) filterParams.get("userName");
+        if (StringUtils.isNotEmpty(userName)) {
+          builder.setUserName(userName);
+        }
+      }
+      if (filterParams.containsKey("filterByOperator")) {
+        final String filterByOperator = (String) filterParams.get("filterByOperator");
+        if (StringUtils.isNotEmpty(filterByOperator)) {
+          if (filterByOperator.toUpperCase().equals("AND")) {
+            filterByAnd = true;
+          }
+        }
+      }
+    }
+    if (filterByAnd) {
+      builder.setFilterByOperator(SlowLogResponseRequest.FilterByOperator.AND);
+    } else {
+      builder.setFilterByOperator(SlowLogResponseRequest.FilterByOperator.OR);
+    }
+    SlowLogResponseRequest slowLogResponseRequest = builder.build();
+    return HBaseProtos.LogRequest.newBuilder()
+      .setLogClassName(slowLogResponseRequest.getClass().getName())
+      .setLogMessage(slowLogResponseRequest.toByteString())
+      .build();
+  }
+
+  /**
+   * Create a protocol buffer {@link ClearSlowLogResponseRequest}
+   *
+   * @return a protocol buffer ClearSlowLogResponseRequest
+   */
+  public static ClearSlowLogResponseRequest buildClearSlowLogResponseRequest() {
+    return ClearSlowLogResponseRequest.newBuilder().build();
+  }
+
 }

hbase-client/src/main/java/org/apache/hadoop/hbase/slowlog/SlowLogTableAccessor.java

@@ -0,0 +1,154 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.slowlog;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.NamespaceDescriptor;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.client.Connection;
+import org.apache.hadoop.hbase.client.ConnectionFactory;
+import org.apache.hadoop.hbase.client.Durability;
+import org.apache.hadoop.hbase.client.Put;
+import org.apache.hadoop.hbase.client.Table;
+import org.apache.hadoop.hbase.protobuf.generated.TooSlowLog;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Slowlog Accessor to record slow/large RPC log identified at each RegionServer RpcServer level.
+ * This can be done only optionally to record the entire history of slow/large rpc calls
+ * since RingBuffer can handle only limited latest records.
+ */
+@InterfaceAudience.Private
+public final class SlowLogTableAccessor {
+
+  private static final Logger LOG = LoggerFactory.getLogger(SlowLogTableAccessor.class);
+
+  private static final Random RANDOM = new Random();
+
+  private static Connection connection;
+
+  private SlowLogTableAccessor() {
+  }
+
+  /**
+   * hbase:slowlog table name - can be enabled
+   * with config - hbase.regionserver.slowlog.systable.enabled
+   */
+  public static final TableName SLOW_LOG_TABLE_NAME =
+    TableName.valueOf(NamespaceDescriptor.SYSTEM_NAMESPACE_NAME_STR, "slowlog");
+
+  private static void doPut(final Connection connection, final List<Put> puts)
+    throws IOException {
+    try (Table table = connection.getTable(SLOW_LOG_TABLE_NAME)) {
+      table.put(puts);
+    }
+  }
+
+  /**
+   * Add slow/large log records to hbase:slowlog table
+   * @param slowLogPayloads List of SlowLogPayload to process
+   * @param configuration Configuration to use for connection
+   */
+  public static void addSlowLogRecords(final List<TooSlowLog.SlowLogPayload> slowLogPayloads,
+    final Configuration configuration) {
+    List<Put> puts = new ArrayList<>(slowLogPayloads.size());
+    for (TooSlowLog.SlowLogPayload slowLogPayload : slowLogPayloads) {
+      final byte[] rowKey = getRowKey(slowLogPayload);
+      final Put put = new Put(rowKey);
+      put.setDurability(Durability.SKIP_WAL);
+      put.setPriority(HConstants.NORMAL_QOS);
+      put.addColumn(HConstants.SLOWLOG_INFO_FAMILY, Bytes.toBytes("call_details"),
+        Bytes.toBytes(slowLogPayload.getCallDetails()))
+        .addColumn(HConstants.SLOWLOG_INFO_FAMILY, Bytes.toBytes("client_address"),
+          Bytes.toBytes(slowLogPayload.getClientAddress()))
+        .addColumn(HConstants.SLOWLOG_INFO_FAMILY, Bytes.toBytes("method_name"),
+          Bytes.toBytes(slowLogPayload.getMethodName()))
+        .addColumn(HConstants.SLOWLOG_INFO_FAMILY, Bytes.toBytes("param"),
+          Bytes.toBytes(slowLogPayload.getParam()))
+        .addColumn(HConstants.SLOWLOG_INFO_FAMILY, Bytes.toBytes("processing_time"),
+          Bytes.toBytes(Integer.toString(slowLogPayload.getProcessingTime())))
+        .addColumn(HConstants.SLOWLOG_INFO_FAMILY, Bytes.toBytes("queue_time"),
+          Bytes.toBytes(Integer.toString(slowLogPayload.getQueueTime())))
+        .addColumn(HConstants.SLOWLOG_INFO_FAMILY, Bytes.toBytes("region_name"),
+          Bytes.toBytes(slowLogPayload.getRegionName()))
+        .addColumn(HConstants.SLOWLOG_INFO_FAMILY, Bytes.toBytes("response_size"),
+          Bytes.toBytes(Long.toString(slowLogPayload.getResponseSize())))
+        .addColumn(HConstants.SLOWLOG_INFO_FAMILY, Bytes.toBytes("server_class"),
+          Bytes.toBytes(slowLogPayload.getServerClass()))
+        .addColumn(HConstants.SLOWLOG_INFO_FAMILY, Bytes.toBytes("start_time"),
+          Bytes.toBytes(Long.toString(slowLogPayload.getStartTime())))
+        .addColumn(HConstants.SLOWLOG_INFO_FAMILY, Bytes.toBytes("type"),
+          Bytes.toBytes(slowLogPayload.getType().name()))
+        .addColumn(HConstants.SLOWLOG_INFO_FAMILY, Bytes.toBytes("username"),
+          Bytes.toBytes(slowLogPayload.getUserName()));
+      puts.add(put);
+    }
+    try {
+      if (connection == null) {
+        createConnection(configuration);
+      }
+      doPut(connection, puts);
+    } catch (Exception e) {
+      LOG.warn("Failed to add slow/large log records to hbase:slowlog table.", e);
+    }
+  }
+
+  private static synchronized void createConnection(Configuration configuration)
+    throws IOException {
+    Configuration conf = new Configuration(configuration);
+    // rpc timeout: 20s
+    conf.setInt(HConstants.HBASE_RPC_TIMEOUT_KEY, 20000);
+    // retry count: 5
+    conf.setInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER, 5);
+    conf.setInt("hbase.client.serverside.retries.multiplier", 1);
+    connection = ConnectionFactory.createConnection(conf);
+  }
+
+  /**
+   * Create rowKey: currentTimeMillis APPEND slowLogPayload.hashcode
+   * Scan on slowlog table should keep records with sorted order of time, however records
+   * added at the very same time (currentTimeMillis) could be in random order.
+   *
+   * @param slowLogPayload SlowLogPayload to process
+   * @return rowKey byte[]
+   */
+  private static byte[] getRowKey(final TooSlowLog.SlowLogPayload slowLogPayload) {
+    String hashcode = String.valueOf(slowLogPayload.hashCode());
+    String lastFiveDig =
+      hashcode.substring((hashcode.length() > 5) ? (hashcode.length() - 5) : 0);
+    if (lastFiveDig.startsWith("-")) {
+      lastFiveDig = String.valueOf(RANDOM.nextInt(99999));
+    }
+    final long currentTimeMillis = EnvironmentEdgeManager.currentTime();
+    final String timeAndHashcode = currentTimeMillis + lastFiveDig;
+    final long rowKeyLong = Long.parseLong(timeAndHashcode);
+    return Bytes.toBytes(rowKeyLong);
+  }
+
+}

hbase-common/src/main/java/org/apache/hadoop/hbase/HConstants.java

@@ -1401,6 +1401,22 @@ public final class HConstants {
    */
   public static final int BATCH_ROWS_THRESHOLD_DEFAULT = 5000;
 
+  public static final int DEFAULT_SLOW_LOG_RING_BUFFER_SIZE = 256;
+
+  public static final String SLOW_LOG_BUFFER_ENABLED_KEY =
+    "hbase.regionserver.slowlog.buffer.enabled";
+  public static final boolean DEFAULT_ONLINE_LOG_PROVIDER_ENABLED = false;
+
+  /** The slowlog info family as a string*/
+  private static final String SLOWLOG_INFO_FAMILY_STR = "info";
+
+  /** The slowlog info family */
+  public static final byte [] SLOWLOG_INFO_FAMILY = Bytes.toBytes(SLOWLOG_INFO_FAMILY_STR);
+
+  public static final String SLOW_LOG_SYS_TABLE_ENABLED_KEY =
+    "hbase.regionserver.slowlog.systable.enabled";
+  public static final boolean DEFAULT_SLOW_LOG_SYS_TABLE_ENABLED_KEY = false;
+
   private HConstants() {
     // Can't be instantiated with this ctor.
   }

hbase-common/src/main/resources/hbase-default.xml

@@ -1690,4 +1690,60 @@ possible configurations would overwhelm and obscure the important.
       too large batch request.
     </description>
   </property>
+  <property>
+    <name>hbase.regionserver.slowlog.ringbuffer.size</name>
+    <value>256</value>
+    <description>
+      Default size of ringbuffer to be maintained by each RegionServer in order
+      to store online slowlog responses. This is an in-memory ring buffer of
+      requests that were judged to be too slow in addition to the responseTooSlow
+      logging. The in-memory representation would be complete.
+      For more details, please look into Doc Section:
+      Get Slow Response Log from shell
+    </description>
+  </property>
+  <property>
+    <name>hbase.regionserver.slowlog.buffer.enabled</name>
+    <value>false</value>
+    <description>
+      Indicates whether RegionServers have ring buffer running for storing
+      Online Slow logs in FIFO manner with limited entries. The size of
+      the ring buffer is indicated by config: hbase.regionserver.slowlog.ringbuffer.size
+      The default value is false, turn this on and get latest slowlog
+      responses with complete data.
+    </description>
+  </property>
+  <property>
+    <name>hbase.regionserver.slowlog.systable.enabled</name>
+    <value>false</value>
+    <description>
+      Should be enabled only if hbase.regionserver.slowlog.buffer.enabled is enabled. If enabled
+      (true), all slow/large RPC logs would be persisted to system table hbase:slowlog (in addition
+      to in-memory ring buffer at each RegionServer). The records are stored in increasing
+      order of time. Operators can scan the table with various combination of ColumnValueFilter.
+      More details are provided in the doc section:
+      "Get Slow/Large Response Logs from System table hbase:slowlog"
+    </description>
+  </property>
+  <property>
+    <name>hbase.namedqueue.provider.classes</name>
+    <value>org.apache.hadoop.hbase.namequeues.impl.SlowLogQueueService,org.apache.hadoop.hbase.namequeues.impl.BalancerDecisionQueueService</value>
+    <description>
+      Default values for NamedQueueService implementors. This comma separated full class names
+      represent all implementors of NamedQueueService that we would like to be invoked by
+      LogEvent handler service. One example of NamedQueue service is SlowLogQueueService which
+      is used to store slow/large RPC logs in ringbuffer at each RegionServer.
+      All implementors of NamedQueueService should be found under package:
+      "org.apache.hadoop.hbase.namequeues.impl"
+    </description>
+  </property>
+  <property>
+    <name>hbase.master.balancer.decision.buffer.enabled</name>
+    <value>false</value>
+    <description>
+      Indicates whether active HMaster has ring buffer running for storing
+      balancer decisions in FIFO manner with limited entries. The size of
+      the ring buffer is indicated by config: hbase.master.balancer.decision.queue.size
+    </description>
+  </property>
 </configuration>

hbase-protocol/pom.xml

@@ -191,6 +191,7 @@
                           <include>Procedure.proto</include>
                           <include>Quota.proto</include>
                           <include>RPC.proto</include>
+                          <include>RecentLogs.proto</include>
                           <include>RegionNormalizer.proto</include>
                           <include>RegionServerStatus.proto</include>
                           <include>RowProcessor.proto</include>
@@ -201,6 +202,7 @@
                           <include>Snapshot.proto</include>
                           <include>SnapshotCleanup.proto</include>
                           <include>Table.proto</include>
+                          <include>TooSlowLog.proto</include>
                           <include>Tracing.proto</include>
                           <include>VisibilityLabels.proto</include>
                           <include>WAL.proto</include>

hbase-protocol/src/main/protobuf/Admin.proto

@@ -28,6 +28,7 @@ option optimize_for = SPEED;
 import "Client.proto";
 import "HBase.proto";
 import "WAL.proto";
+import "TooSlowLog.proto";
 
 message GetRegionInfoRequest {
   required RegionSpecifier region = 1;
@@ -264,6 +265,52 @@ message UpdateConfigurationRequest {
 message UpdateConfigurationResponse {
 }
 
+/**
+ * Slow/Large log (LogRequest) use-case specific RPC request. This request payload will be
+ * converted in bytes and sent to generic RPC API: GetLogEntries
+ * LogRequest message has two params:
+ * 1. log_class_name: SlowLogResponseRequest (for Slow/Large log use-case)
+ * 2. log_message: SlowLogResponseRequest converted in bytes (for Slow/Large log use-case)
+ */
+message SlowLogResponseRequest {
+  enum FilterByOperator {
+    AND = 0;
+    OR = 1;
+  }
+
+  enum LogType {
+    SLOW_LOG = 0;
+    LARGE_LOG = 1;
+  }
+
+  optional string region_name = 1;
+  optional string table_name = 2;
+  optional string client_address = 3;
+  optional string user_name = 4;
+  optional uint32 limit = 5 [default = 10];
+  optional FilterByOperator filter_by_operator = 6 [default = OR];
+  optional LogType log_type = 7;
+}
+
+/**
+ * Slow/Large log (LogEntry) use-case specific RPC response. This response payload will be
+ * converted in bytes by servers and sent as response to generic RPC API: GetLogEntries
+ * LogEntry message has two params:
+ * 1. log_class_name: SlowLogResponses (for Slow/Large log use-case)
+ * 2. log_message: SlowLogResponses converted in bytes (for Slow/Large log use-case)
+ */
+message SlowLogResponses {
+  repeated SlowLogPayload slow_log_payloads = 1;
+}
+
+message ClearSlowLogResponseRequest {
+
+}
+
+message ClearSlowLogResponses {
+  required bool is_cleaned = 1;
+}
+
 service AdminService {
   rpc GetRegionInfo(GetRegionInfoRequest)
     returns(GetRegionInfoResponse);
@@ -318,4 +365,11 @@ service AdminService {
 
   rpc UpdateConfiguration(UpdateConfigurationRequest)
     returns(UpdateConfigurationResponse);
+
+  rpc ClearSlowLogsResponses(ClearSlowLogResponseRequest)
+    returns(ClearSlowLogResponses);
+
+  rpc GetLogEntries(LogRequest)
+    returns(LogEntry);
+
 }

hbase-protocol/src/main/protobuf/HBase.proto

@@ -256,6 +256,16 @@ message SnapshotDescription {
   optional int64 ttl = 8 [default = 0];
 }
 
+message LogRequest {
+  required string log_class_name = 1;
+  required bytes log_message = 2;
+}
+
+message LogEntry {
+  required string log_class_name = 1;
+  required bytes log_message = 2;
+}
+
 message RegionLocation {
   required RegionInfo region_info = 1;
   optional ServerName server_name = 2;

hbase-protocol/src/main/protobuf/Master.proto

@@ -34,6 +34,7 @@ import "ErrorHandling.proto";
 import "Procedure.proto";
 import "Quota.proto";
 import "Snapshot.proto";
+import "RecentLogs.proto";
 
 /* Column-level protobufs */
 
@@ -595,6 +596,28 @@ message IsSnapshotCleanupEnabledResponse {
   required bool enabled = 1;
 }
 
+/**
+ * BalancerDecision (LogRequest) use-case specific RPC request. This request payload will be
+ * converted in bytes and sent to generic RPC API: GetLogEntries
+ * LogRequest message has two params:
+ * 1. log_class_name: BalancerDecisionsRequest (for BalancerDecision use-case)
+ * 2. log_message: BalancerDecisionsRequest converted in bytes (for BalancerDecision use-case)
+ */
+message BalancerDecisionsRequest {
+  optional uint32 limit = 1;
+}
+
+/**
+ * BalancerDecision (LogEntry) use-case specific RPC response. This response payload will be
+ * converted in bytes by servers and sent as response to generic RPC API: GetLogEntries
+ * LogEntry message has two params:
+ * 1. log_class_name: BalancerDecisionsResponse (for BalancerDecision use-case)
+ * 2. log_message: BalancerDecisionsResponse converted in bytes (for BalancerDecision use-case)
+ */
+message BalancerDecisionsResponse {
+  repeated BalancerDecision balancer_decision = 1;
+}
+
 
 service MasterService {
   /** Used by the client to get the number of regions that have received the updated schema */
@@ -909,6 +932,9 @@ service MasterService {
   rpc IsSnapshotCleanupEnabled (IsSnapshotCleanupEnabledRequest)
     returns (IsSnapshotCleanupEnabledResponse);
 
+  rpc GetLogEntries(LogRequest)
+    returns(LogEntry);
+
   /** returns table state */
   rpc GetTableState(GetTableStateRequest)
     returns(GetTableStateResponse);

hbase-protocol/src/main/protobuf/RecentLogs.proto

@@ -0,0 +1,37 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// This file contains protocol buffers that are used for Online BalancerDecision history
+// To be used as Ring Buffer payload
+package hbase.pb;
+
+option java_package = "org.apache.hadoop.hbase.protobuf.generated";
+option java_outer_classname = "RecentLogs";
+option java_generate_equals_and_hash = true;
+option optimize_for = SPEED;
+
+message BalancerDecision {
+
+  required string initial_function_costs = 1;
+  required string final_function_costs = 2;
+  required double init_total_cost = 3;
+  required double computed_total_cost = 4;
+  required uint64 computed_steps = 5;
+  repeated string region_plans = 6;
+
+}

hbase-protocol/src/main/protobuf/TooSlowLog.proto

@@ -0,0 +1,54 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// This file contains protocol buffers that are used for Online TooSlowLogs
+// To be used as Ring Buffer payload
+package hbase.pb;
+
+option java_package = "org.apache.hadoop.hbase.protobuf.generated";
+option java_outer_classname = "TooSlowLog";
+option java_generate_equals_and_hash = true;
+option optimize_for = SPEED;
+
+message SlowLogPayload {
+  required int64 start_time = 1;
+  required int32 processing_time = 2;
+  required int32 queue_time = 3;
+  required int64 response_size = 4;
+  required string client_address = 5;
+  required string server_class = 6;
+  required string method_name = 7;
+  required string call_details = 8;
+  optional string param = 9;
+  required string user_name = 10;
+  optional string region_name = 11;
+  optional int32 multi_gets = 12 [default = 0];
+  optional int32 multi_mutations = 13 [default = 0];
+  optional int32 multi_service_calls = 14 [default = 0];
+  required Type type = 15;
+
+  // SLOW_LOG is RPC call slow in nature whereas LARGE_LOG is RPC call quite large.
+  // Majority of times, slow logs are also large logs and hence, ALL is combination of
+  // both
+  enum Type {
+    SLOW_LOG = 0;
+    LARGE_LOG = 1;
+    ALL = 2;
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/RpcServer.java

@@ -97,6 +97,8 @@ import org.apache.hadoop.hbase.io.ByteBufferInputStream;
 import org.apache.hadoop.hbase.io.ByteBufferOutputStream;
 import org.apache.hadoop.hbase.monitoring.MonitoredRPCHandler;
 import org.apache.hadoop.hbase.monitoring.TaskMonitor;
+import org.apache.hadoop.hbase.namequeues.NamedQueueRecorder;
+import org.apache.hadoop.hbase.namequeues.RpcLogDetails;
 import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos;
 import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.VersionInfo;
@@ -168,6 +170,7 @@ public class RpcServer implements RpcServerInterface, ConfigurationObserver {
       = new CallQueueTooBigException();
 
   private final boolean authorize;
+  private final boolean isOnlineLogProviderEnabled;
   private boolean isSecurityEnabled;
 
   public static final byte CURRENT_VERSION = 0;
@@ -309,6 +312,12 @@ public class RpcServer implements RpcServerInterface, ConfigurationObserver {
    */
   private RSRpcServices rsRpcServices;
 
+
+  /**
+   * Use to add online slowlog responses
+   */
+  private NamedQueueRecorder namedQueueRecorder;
+
   /**
    * Datastructure that holds all necessary to a method invocation and then afterward, carries
    * the result.
@@ -2254,6 +2263,8 @@ public class RpcServer implements RpcServerInterface, ConfigurationObserver {
     }
     initReconfigurable(conf);
 
+    this.isOnlineLogProviderEnabled = conf.getBoolean(HConstants.SLOW_LOG_BUFFER_ENABLED_KEY,
+      HConstants.DEFAULT_ONLINE_LOG_PROVIDER_ENABLED);
     this.scheduler = scheduler;
     this.scheduler.init(new RpcSchedulerContext(this));
   }
@@ -2433,13 +2444,19 @@ public class RpcServer implements RpcServerInterface, ConfigurationObserver {
       boolean tooSlow = (processingTime > warnResponseTime && warnResponseTime > -1);
       boolean tooLarge = (responseSize > warnResponseSize && warnResponseSize > -1);
       if (tooSlow || tooLarge) {
+        final String userName = call.getRequestUserName() != null ? call.getRequestUserName() : "";
         // when tagging, we let TooLarge trump TooSmall to keep output simple
         // note that large responses will often also be slow.
-        logResponse(param,
+        logResponse(param, md.getName(), md.getName() + "(" + param.getClass().getName() + ")",
-            md.getName(), md.getName() + "(" + param.getClass().getName() + ")",
+          tooLarge, tooSlow, status.getClient(), startTime, processingTime, qTime, responseSize);
-            (tooLarge ? "TooLarge" : "TooSlow"),
+        if (this.namedQueueRecorder != null && this.isOnlineLogProviderEnabled) {
-            status.getClient(), startTime, processingTime, qTime,
+          // send logs to ring buffer owned by slowLogRecorder
-            responseSize);
+          final String className =
+            server == null ? "" : server.getClass().getSimpleName();
+          this.namedQueueRecorder.addRecord(
+            new RpcLogDetails(md, param, status.getClient(), responseSize, className, tooSlow,
+              tooLarge, receiveTime, startTime, userName));
+        }
       }
       return new Pair<Message, CellScanner>(result, controller.cellScanner());
     } catch (Throwable e) {
@@ -2470,7 +2487,8 @@ public class RpcServer implements RpcServerInterface, ConfigurationObserver {
    * @param param The parameters received in the call.
    * @param methodName The name of the method invoked
    * @param call The string representation of the call
-   * @param tag  The tag that will be used to indicate this event in the log.
+   * @param tooLarge To indicate if the event is tooLarge
+   * @param tooSlow To indicate if the event is tooSlow
    * @param clientAddress The address of the client who made this call.
    * @param startTime The time that the call was initiated, in ms.
    * @param processingTime The duration that the call took to run, in ms.
@@ -2478,9 +2496,8 @@ public class RpcServer implements RpcServerInterface, ConfigurationObserver {
    *   prior to being initiated, in ms.
    * @param responseSize The size in bytes of the response buffer.
    */
-  void logResponse(Message param, String methodName, String call, String tag,
+  void logResponse(Message param, String methodName, String call, boolean tooLarge, boolean tooSlow,
-      String clientAddress, long startTime, int processingTime, int qTime,
+      String clientAddress, long startTime, int processingTime, int qTime, long responseSize)
-      long responseSize)
       throws IOException {
     // base information that is reported regardless of type of call
     Map<String, Object> responseInfo = new HashMap<String, Object>();
@@ -2534,6 +2551,8 @@ public class RpcServer implements RpcServerInterface, ConfigurationObserver {
       responseInfo.put("multi.mutations", numMutations);
       responseInfo.put("multi.servicecalls", numServiceCalls);
     }
+    final String tag = (tooLarge && tooSlow) ? "TooLarge & TooSlow"
+      : (tooSlow ? "TooSlow" : "TooLarge");
     LOG.warn("(response" + tag + "): " + GSON.toJson(responseInfo));
   }
 
@@ -2881,4 +2900,10 @@ public class RpcServer implements RpcServerInterface, ConfigurationObserver {
   public void setRsRpcServices(RSRpcServices rsRpcServices) {
     this.rsRpcServices = rsRpcServices;
   }
+
+  @Override
+  public void setNamedQueueRecorder(NamedQueueRecorder namedQueueRecorder) {
+    this.namedQueueRecorder = namedQueueRecorder;
+  }
+
 }

hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/RpcServerInterface.java

@@ -28,6 +28,7 @@ import org.apache.hadoop.hbase.classification.InterfaceStability;
 import org.apache.hadoop.hbase.CellScanner;
 import org.apache.hadoop.hbase.HBaseInterfaceAudience;
 import org.apache.hadoop.hbase.monitoring.MonitoredRPCHandler;
+import org.apache.hadoop.hbase.namequeues.NamedQueueRecorder;
 import org.apache.hadoop.hbase.regionserver.RSRpcServices;
 import org.apache.hadoop.hbase.util.Pair;
 import org.apache.hadoop.security.authorize.PolicyProvider;
@@ -88,4 +89,12 @@ public interface RpcServerInterface {
   RpcScheduler getScheduler();
 
   void setRsRpcServices(RSRpcServices rsRpcServices);
+
+  /**
+   * Set Online SlowLog Provider
+   *
+   * @param namedQueueRecorder instance of {@link NamedQueueRecorder}
+   */
+  void setNamedQueueRecorder(final NamedQueueRecorder namedQueueRecorder);
+
 }

hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java

@@ -128,6 +128,7 @@ import org.apache.hadoop.hbase.master.procedure.ModifyTableProcedure;
 import org.apache.hadoop.hbase.master.procedure.ProcedurePrepareLatch;
 import org.apache.hadoop.hbase.master.procedure.ProcedureSyncWait;
 import org.apache.hadoop.hbase.master.procedure.TruncateTableProcedure;
+import org.apache.hadoop.hbase.master.slowlog.SlowLogMasterService;
 import org.apache.hadoop.hbase.master.snapshot.SnapshotManager;
 import org.apache.hadoop.hbase.monitoring.MemoryBoundedLogMessageBuffer;
 import org.apache.hadoop.hbase.monitoring.MonitoredTask;
@@ -945,6 +946,9 @@ public class HMaster extends HRegionServer implements MasterServices, Server {
     status.setStatus("Starting quota manager");
     initQuotaManager();
 
+    final SlowLogMasterService slowLogMasterService = new SlowLogMasterService(conf, this);
+    slowLogMasterService.init();
+
     // assign the meta replicas
     Set<ServerName> EMPTY_SET = new HashSet<ServerName>();
     int numReplicas = conf.getInt(HConstants.META_REPLICAS_NUM,

hbase-server/src/main/java/org/apache/hadoop/hbase/master/MasterRpcServices.java

@@ -19,6 +19,8 @@
 package org.apache.hadoop.hbase.master;
 
 import java.io.IOException;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.net.InetAddress;
 import java.util.ArrayList;
 import java.util.HashSet;
@@ -53,6 +55,10 @@ import org.apache.hadoop.hbase.ipc.QosPriority;
 import org.apache.hadoop.hbase.ipc.RpcServer;
 import org.apache.hadoop.hbase.ipc.RpcServer.BlockingServiceAndInterface;
 import org.apache.hadoop.hbase.ipc.ServerRpcController;
+import org.apache.hadoop.hbase.namequeues.BalancerDecisionDetails;
+import org.apache.hadoop.hbase.namequeues.NamedQueueRecorder;
+import org.apache.hadoop.hbase.namequeues.request.NamedQueueGetRequest;
+import org.apache.hadoop.hbase.namequeues.response.NamedQueueGetResponse;
 import org.apache.hadoop.hbase.procedure.MasterProcedureManager;
 import org.apache.hadoop.hbase.procedure2.Procedure;
 import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
@@ -288,6 +294,51 @@ public class MasterRpcServices extends RSRpcServices
     }
   }
 
+  @Override
+  public HBaseProtos.LogEntry getLogEntries(RpcController controller,
+      HBaseProtos.LogRequest request) throws ServiceException {
+    try {
+      final String logClassName = request.getLogClassName();
+      Class<?> logClass = Class.forName(logClassName)
+        .asSubclass(Message.class);
+      Method method = logClass.getMethod("parseFrom", ByteString.class);
+      if (logClassName.contains("BalancerDecisionsRequest")) {
+        MasterProtos.BalancerDecisionsRequest balancerDecisionsRequest =
+          (MasterProtos.BalancerDecisionsRequest) method
+            .invoke(null, request.getLogMessage());
+        MasterProtos.BalancerDecisionsResponse balancerDecisionsResponse =
+          getBalancerDecisions(balancerDecisionsRequest);
+        return HBaseProtos.LogEntry.newBuilder()
+          .setLogClassName(balancerDecisionsResponse.getClass().getName())
+          .setLogMessage(balancerDecisionsResponse.toByteString())
+          .build();
+      }
+    } catch (ClassNotFoundException | NoSuchMethodException | IllegalAccessException
+      | InvocationTargetException e) {
+      LOG.error("Error while retrieving log entries.", e);
+      throw new ServiceException(e);
+    }
+    throw new ServiceException("Invalid request params");
+  }
+
+  private MasterProtos.BalancerDecisionsResponse getBalancerDecisions(
+      MasterProtos.BalancerDecisionsRequest request) {
+    final NamedQueueRecorder namedQueueRecorder = this.regionServer.getNamedQueueRecorder();
+    if (namedQueueRecorder == null) {
+      return MasterProtos.BalancerDecisionsResponse.newBuilder()
+        .addAllBalancerDecision(new ArrayList<RecentLogs.BalancerDecision>()).build();
+    }
+    final NamedQueueGetRequest namedQueueGetRequest = new NamedQueueGetRequest();
+    namedQueueGetRequest.setNamedQueueEvent(BalancerDecisionDetails.BALANCER_DECISION_EVENT);
+    namedQueueGetRequest.setBalancerDecisionsRequest(request);
+    NamedQueueGetResponse namedQueueGetResponse =
+      namedQueueRecorder.getNamedQueueRecords(namedQueueGetRequest);
+    List<RecentLogs.BalancerDecision> balancerDecisions =
+      namedQueueGetResponse.getBalancerDecisions();
+    return MasterProtos.BalancerDecisionsResponse.newBuilder()
+      .addAllBalancerDecision(balancerDecisions).build();
+  }
+
   enum BalanceSwitchMode {
     SYNC,
     ASYNC

hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/BaseLoadBalancer.java

@@ -51,6 +51,7 @@ import org.apache.hadoop.hbase.master.MasterServices;
 import org.apache.hadoop.hbase.master.RackManager;
 import org.apache.hadoop.hbase.master.RegionPlan;
 import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer.Cluster.Action.Type;
+import org.apache.hadoop.hbase.namequeues.NamedQueueRecorder;
 import org.apache.hadoop.util.StringUtils;
 
 import com.google.common.annotations.VisibleForTesting;
@@ -67,6 +68,11 @@ import com.google.common.collect.Sets;
  *
  */
 public abstract class BaseLoadBalancer implements LoadBalancer {
+
+  public static final String BALANCER_DECISION_BUFFER_ENABLED =
+    "hbase.master.balancer.decision.buffer.enabled";
+  public static final boolean DEFAULT_BALANCER_DECISION_BUFFER_ENABLED = false;
+
   protected static final int MIN_SERVER_BALANCE = 2;
   private volatile boolean stopped = false;
 
@@ -75,6 +81,11 @@ public abstract class BaseLoadBalancer implements LoadBalancer {
   protected RegionLocationFinder regionFinder;
   protected boolean useRegionFinder;
 
+  /**
+   * Use to add balancer decision history to ring-buffer
+   */
+  protected NamedQueueRecorder namedQueueRecorder;
+
   private static class DefaultRackManager extends RackManager {
     @Override
     public String getRack(ServerName server) {

hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/StochasticLoadBalancer.java

@@ -43,6 +43,7 @@ import org.apache.hadoop.hbase.RegionLoad;
 import org.apache.hadoop.hbase.ServerLoad;
 import org.apache.hadoop.hbase.ServerName;
 import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.client.BalancerDecision;
 import org.apache.hadoop.hbase.master.MasterServices;
 import org.apache.hadoop.hbase.master.RegionPlan;
 import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer.Cluster.Action;
@@ -51,6 +52,8 @@ import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer.Cluster.AssignRe
 import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer.Cluster.LocalityType;
 import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer.Cluster.MoveRegionAction;
 import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer.Cluster.SwapRegionsAction;
+import org.apache.hadoop.hbase.namequeues.BalancerDecisionDetails;
+import org.apache.hadoop.hbase.namequeues.NamedQueueRecorder;
 import org.apache.hadoop.hbase.regionserver.compactions.OffPeakHours;
 import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
 import org.apache.hadoop.hbase.util.ReflectionUtils;
@@ -232,6 +235,13 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
     curFunctionCosts = new Double[costFunctions.size()];
     tempFunctionCosts = new Double[costFunctions.size()];
 
+    boolean isBalancerDecisionRecording = getConf()
+      .getBoolean(BaseLoadBalancer.BALANCER_DECISION_BUFFER_ENABLED,
+        BaseLoadBalancer.DEFAULT_BALANCER_DECISION_BUFFER_ENABLED);
+    if (this.namedQueueRecorder == null && isBalancerDecisionRecording) {
+      this.namedQueueRecorder = NamedQueueRecorder.getInstance(getConf());
+    }
+
     LOG.info("Loaded config; maxSteps=" + maxSteps + ", stepsPerRegion=" + stepsPerRegion +
             ", maxRunningTime=" + maxRunningTime + ", isByTable=" + isByTable + ", etc." +
             ", maxRunningTime=" + maxRunningTime + ", isByTable=" + isByTable + ", CostFunctions=" +
@@ -430,7 +440,7 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
     System.arraycopy(tempFunctionCosts, 0, curFunctionCosts, 0, this.curFunctionCosts.length);
 
     double initCost = currentCost;
-    double newCost = currentCost;
+    double newCost;
 
     long computedMaxSteps = 0;
     if (runMaxSteps) {
@@ -452,6 +462,7 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
     LOG.info("start StochasticLoadBalancer.balancer, initCost=" + currentCost + ", functionCost="
         + functionCost() + " computedMaxSteps: " + computedMaxSteps);
 
+    final String initFunctionTotalCosts = totalCostsPerFunc();
     // Perform a stochastic walk to see if we can get a good fit.
     long step;
 
@@ -502,7 +513,7 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
             + plans.size() + " regions; Going from a computed cost of "
             + initCost + " to a new cost of " + currentCost);
       }
-
+      sendRegionPlansToRingBuffer(plans, currentCost, initCost, initFunctionTotalCosts, step);
       return plans;
     }
     if (LOG.isDebugEnabled()) {
@@ -513,6 +524,27 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
     return null;
   }
 
+  private void sendRegionPlansToRingBuffer(List<RegionPlan> plans, double currentCost,
+    double initCost, String initFunctionTotalCosts, long step) {
+    if (this.namedQueueRecorder != null) {
+      List<String> regionPlans = new ArrayList<>();
+      for (RegionPlan plan : plans) {
+        regionPlans.add(
+          "table: " + plan.getRegionInfo().getTable() + " , region: " + plan.getRegionName()
+            + " , source: " + plan.getSource() + " , destination: " + plan.getDestination());
+      }
+      BalancerDecision balancerDecision =
+        new BalancerDecision.Builder()
+          .setInitTotalCost(initCost)
+          .setInitialFunctionCosts(initFunctionTotalCosts)
+          .setComputedTotalCost(currentCost)
+          .setFinalFunctionCosts(totalCostsPerFunc())
+          .setComputedSteps(step)
+          .setRegionPlans(regionPlans).build();
+      namedQueueRecorder.addRecord(new BalancerDecisionDetails(balancerDecision));
+    }
+  }
+
   /**
    * update costs to JMX
    */
@@ -557,6 +589,23 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
     return builder.toString();
   }
 
+  private String totalCostsPerFunc() {
+    StringBuilder builder = new StringBuilder();
+    for (CostFunction c : costFunctions) {
+      if (c.getMultiplier() * c.cost() > 0.0) {
+        builder.append(" ");
+        builder.append(c.getClass().getSimpleName());
+        builder.append(" : ");
+        builder.append(c.getMultiplier() * c.cost());
+        builder.append(";");
+      }
+    }
+    if (builder.length() > 0) {
+      builder.deleteCharAt(builder.length() - 1);
+    }
+    return builder.toString();
+  }
+
   /**
    * Create all of the RegionPlan's needed to move from the initial cluster state to the desired
    * state.

hbase-server/src/main/java/org/apache/hadoop/hbase/master/slowlog/SlowLogMasterService.java

@@ -0,0 +1,73 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.master.slowlog;
+
+import java.io.IOException;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.HColumnDescriptor;
+import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.HTableDescriptor;
+import org.apache.hadoop.hbase.MetaTableAccessor;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.master.MasterServices;
+import org.apache.hadoop.hbase.slowlog.SlowLogTableAccessor;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Slowlog Master services - Table creation to be used by HMaster
+ */
+@InterfaceAudience.Private
+public class SlowLogMasterService {
+
+  private static final Logger LOG = LoggerFactory.getLogger(SlowLogMasterService.class);
+
+  private final boolean slowlogTableEnabled;
+  private final MasterServices masterServices;
+
+  private static final HTableDescriptor TABLE_DESCRIPTOR_BUILDER =
+    new HTableDescriptor(SlowLogTableAccessor.SLOW_LOG_TABLE_NAME).setRegionReplication(1);
+
+  static {
+    TABLE_DESCRIPTOR_BUILDER.addFamily(new HColumnDescriptor(HConstants.SLOWLOG_INFO_FAMILY)
+      .setScope(HConstants.REPLICATION_SCOPE_LOCAL).setBlockCacheEnabled(false).setMaxVersions(1));
+  }
+
+  public SlowLogMasterService(final Configuration configuration,
+    final MasterServices masterServices) {
+    slowlogTableEnabled = configuration.getBoolean(HConstants.SLOW_LOG_SYS_TABLE_ENABLED_KEY,
+      HConstants.DEFAULT_SLOW_LOG_SYS_TABLE_ENABLED_KEY);
+    this.masterServices = masterServices;
+  }
+
+  public void init() throws IOException {
+    if (!slowlogTableEnabled) {
+      LOG.info("Slow/Large requests logging to system table hbase:slowlog is disabled. Quitting.");
+      return;
+    }
+    if (!MetaTableAccessor
+        .tableExists(masterServices.getConnection(), SlowLogTableAccessor.SLOW_LOG_TABLE_NAME)) {
+      LOG.info("slowlog table not found. Creating.");
+      this.masterServices.createSystemTable(TABLE_DESCRIPTOR_BUILDER);
+    }
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/BalancerDecisionDetails.java

@@ -0,0 +1,51 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import org.apache.commons.lang.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.client.BalancerDecision;
+
+/**
+ * Balancer decision details that would be passed on to ring buffer for history
+ */
+@InterfaceAudience.Private
+public class BalancerDecisionDetails extends NamedQueuePayload {
+
+  public static final int BALANCER_DECISION_EVENT = 1;
+
+  private final BalancerDecision balancerDecision;
+
+  public BalancerDecisionDetails(BalancerDecision balancerDecision) {
+    super(BALANCER_DECISION_EVENT);
+    this.balancerDecision = balancerDecision;
+  }
+
+  public BalancerDecision getBalancerDecision() {
+    return balancerDecision;
+  }
+
+  @Override
+  public String toString() {
+    return new ToStringBuilder(this)
+      .append("balancerDecision", balancerDecision)
+      .toString();
+  }
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/DisruptorExceptionHandler.java

@@ -0,0 +1,50 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import com.lmax.disruptor.ExceptionHandler;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Exception Handler for Online Slow Log Ring Buffer
+ */
+@InterfaceAudience.Private
+class DisruptorExceptionHandler implements ExceptionHandler {
+
+  private static final Logger LOG = LoggerFactory.getLogger(DisruptorExceptionHandler.class);
+
+  @Override
+  public void handleEventException(Throwable e, long sequence, Object event) {
+    LOG.error("Sequence={}, event={}", sequence, event, e);
+  }
+
+  @Override
+  public void handleOnStartException(Throwable e) {
+    LOG.error("Disruptor onStartException: ", e);
+  }
+
+  @Override
+  public void handleOnShutdownException(Throwable e) {
+    LOG.error("Disruptor onShutdownException: ", e);
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/LogEventHandler.java

@@ -0,0 +1,128 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import com.lmax.disruptor.EventHandler;
+import com.lmax.disruptor.RingBuffer;
+import java.lang.reflect.InvocationTargetException;
+import java.util.HashMap;
+import java.util.Map;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.namequeues.request.NamedQueueGetRequest;
+import org.apache.hadoop.hbase.namequeues.response.NamedQueueGetResponse;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Event Handler run by disruptor ringbuffer consumer.
+ * Although this is generic implementation for namedQueue, it can have individual queue specific
+ * logic.
+ */
+@InterfaceAudience.Private
+class LogEventHandler implements EventHandler<RingBufferEnvelope> {
+
+  private static final Logger LOG = LoggerFactory.getLogger(LogEventHandler.class);
+
+  // Map that binds namedQueues to corresponding queue service implementation.
+  // If NamedQueue of specific type is enabled, corresponding service will be used to
+  // insert and retrieve records.
+  // Individual queue sizes should be determined based on their individual configs within
+  // each service.
+  private final Map<NamedQueuePayload.NamedQueueEvent, NamedQueueService> namedQueueServices =
+    new HashMap<>();
+
+  private static final String NAMED_QUEUE_PROVIDER_CLASSES = "hbase.namedqueue.provider.classes";
+
+  LogEventHandler(final Configuration conf) {
+    for (String implName : conf.getStringCollection(NAMED_QUEUE_PROVIDER_CLASSES)) {
+      Class<?> clz;
+      try {
+        clz = Class.forName(implName);
+      } catch (ClassNotFoundException e) {
+        LOG.warn("Failed to find NamedQueueService implementor class {}", implName, e);
+        continue;
+      }
+
+      if (!NamedQueueService.class.isAssignableFrom(clz)) {
+        LOG.warn("Class {} is not implementor of NamedQueueService.", clz);
+        continue;
+      }
+
+      // add all service mappings here
+      try {
+        NamedQueueService namedQueueService =
+          (NamedQueueService) clz.getConstructor(Configuration.class).newInstance(conf);
+        namedQueueServices.put(namedQueueService.getEvent(), namedQueueService);
+      } catch (InstantiationException | IllegalAccessException | NoSuchMethodException
+          | InvocationTargetException e) {
+        LOG.warn("Unable to instantiate/add NamedQueueService implementor {} to service map.",
+          clz);
+      }
+    }
+  }
+
+  /**
+   * Called when a publisher has published an event to the {@link RingBuffer}.
+   * This is generic consumer of disruptor ringbuffer and for each new namedQueue that we
+   * add, we should also provide specific consumer logic here.
+   *
+   * @param event published to the {@link RingBuffer}
+   * @param sequence of the event being processed
+   * @param endOfBatch flag to indicate if this is the last event in a batch from
+   *   the {@link RingBuffer}
+   */
+  @Override
+  public void onEvent(RingBufferEnvelope event, long sequence, boolean endOfBatch) {
+    final NamedQueuePayload namedQueuePayload = event.getPayload();
+    // consume ringbuffer payload based on event type
+    namedQueueServices.get(namedQueuePayload.getNamedQueueEvent())
+      .consumeEventFromDisruptor(namedQueuePayload);
+  }
+
+  /**
+   * Cleans up queues maintained by services.
+   *
+   * @param namedQueueEvent type of queue to clear
+   * @return true if queue is cleaned up, false otherwise
+   */
+  boolean clearNamedQueue(NamedQueuePayload.NamedQueueEvent namedQueueEvent) {
+    return namedQueueServices.get(namedQueueEvent).clearNamedQueue();
+  }
+
+  /**
+   * Add all in memory queue records to system table. The implementors can use system table
+   * or direct HDFS file or ZK as persistence system.
+   */
+  void persistAll(NamedQueuePayload.NamedQueueEvent namedQueueEvent) {
+    namedQueueServices.get(namedQueueEvent).persistAll();
+  }
+
+  /**
+   * Retrieve in memory queue records from ringbuffer
+   *
+   * @param request namedQueue request with event type
+   * @return queue records from ringbuffer after filter (if applied)
+   */
+  NamedQueueGetResponse getNamedQueueRecords(NamedQueueGetRequest request) {
+    return namedQueueServices.get(request.getNamedQueueEvent()).getNamedQueueRecords(request);
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/LogHandlerUtils.java

@@ -0,0 +1,107 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import java.util.ArrayList;
+import java.util.List;
+import org.apache.commons.lang.StringUtils;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos;
+import org.apache.hadoop.hbase.protobuf.generated.TooSlowLog;
+
+/**
+ * Event Handler utility class
+ */
+@InterfaceAudience.Private
+public final class LogHandlerUtils {
+
+  private LogHandlerUtils() {
+  }
+
+  private static int getTotalFiltersCount(AdminProtos.SlowLogResponseRequest request) {
+    int totalFilters = 0;
+    if (StringUtils.isNotEmpty(request.getRegionName())) {
+      totalFilters++;
+    }
+    if (StringUtils.isNotEmpty(request.getTableName())) {
+      totalFilters++;
+    }
+    if (StringUtils.isNotEmpty(request.getClientAddress())) {
+      totalFilters++;
+    }
+    if (StringUtils.isNotEmpty(request.getUserName())) {
+      totalFilters++;
+    }
+    return totalFilters;
+  }
+
+  private static List<TooSlowLog.SlowLogPayload> filterLogs(
+      AdminProtos.SlowLogResponseRequest request,
+      List<TooSlowLog.SlowLogPayload> slowLogPayloadList, int totalFilters) {
+    List<TooSlowLog.SlowLogPayload> filteredSlowLogPayloads = new ArrayList<>();
+    final String regionName =
+      StringUtils.isNotEmpty(request.getRegionName()) ? request.getRegionName() : null;
+    final String tableName =
+      StringUtils.isNotEmpty(request.getTableName()) ? request.getTableName() : null;
+    final String clientAddress =
+      StringUtils.isNotEmpty(request.getClientAddress()) ? request.getClientAddress() : null;
+    final String userName =
+      StringUtils.isNotEmpty(request.getUserName()) ? request.getUserName() : null;
+    for (TooSlowLog.SlowLogPayload slowLogPayload : slowLogPayloadList) {
+      int totalFilterMatches = 0;
+      if (slowLogPayload.getRegionName().equals(regionName)) {
+        totalFilterMatches++;
+      }
+      if (tableName != null && slowLogPayload.getRegionName().startsWith(tableName)) {
+        totalFilterMatches++;
+      }
+      if (slowLogPayload.getClientAddress().equals(clientAddress)) {
+        totalFilterMatches++;
+      }
+      if (slowLogPayload.getUserName().equals(userName)) {
+        totalFilterMatches++;
+      }
+      if (request.hasFilterByOperator() && request.getFilterByOperator()
+        .equals(AdminProtos.SlowLogResponseRequest.FilterByOperator.AND)) {
+        // Filter by AND operator
+        if (totalFilterMatches == totalFilters) {
+          filteredSlowLogPayloads.add(slowLogPayload);
+        }
+      } else {
+        // Filter by OR operator
+        if (totalFilterMatches > 0) {
+          filteredSlowLogPayloads.add(slowLogPayload);
+        }
+      }
+    }
+    return filteredSlowLogPayloads;
+  }
+
+  public static List<TooSlowLog.SlowLogPayload> getFilteredLogs(
+      AdminProtos.SlowLogResponseRequest request, List<TooSlowLog.SlowLogPayload> logPayloadList) {
+    int totalFilters = getTotalFiltersCount(request);
+    if (totalFilters > 0) {
+      logPayloadList = filterLogs(request, logPayloadList, totalFilters);
+    }
+    int limit = Math.min(request.getLimit(), logPayloadList.size());
+    return logPayloadList.subList(0, limit);
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/NamedQueuePayload.java

@@ -0,0 +1,72 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+
+/**
+ * Base payload to be prepared by client to send various namedQueue events for in-memory
+ * ring buffer storage in either HMaster or RegionServer.
+ * e.g slowLog responses
+ */
+@InterfaceAudience.Private
+public class NamedQueuePayload {
+
+  public enum NamedQueueEvent {
+    SLOW_LOG(0),
+    BALANCE_DECISION(1);
+
+    private final int value;
+
+    NamedQueueEvent(int i) {
+      this.value = i;
+    }
+
+    public static NamedQueueEvent getEventByOrdinal(int value){
+      switch (value) {
+        case 0: {
+          return SLOW_LOG;
+        }
+        case 1: {
+          return BALANCE_DECISION;
+        }
+        default: {
+          throw new IllegalArgumentException(
+            "NamedQueue event with ordinal " + value + " not defined");
+        }
+      }
+    }
+
+    public int getValue() {
+      return value;
+    }
+  }
+
+  private final NamedQueueEvent namedQueueEvent;
+
+  public NamedQueuePayload(int eventOrdinal) {
+    this.namedQueueEvent = NamedQueueEvent.getEventByOrdinal(eventOrdinal);
+  }
+
+  public NamedQueueEvent getNamedQueueEvent() {
+    return namedQueueEvent;
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/NamedQueueRecorder.java

@@ -0,0 +1,164 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import com.google.common.base.Preconditions;
+import com.lmax.disruptor.BlockingWaitStrategy;
+import com.lmax.disruptor.EventFactory;
+import com.lmax.disruptor.RingBuffer;
+import com.lmax.disruptor.dsl.Disruptor;
+import com.lmax.disruptor.dsl.ProducerType;
+import java.util.concurrent.Executors;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.classification.InterfaceStability;
+import org.apache.hadoop.hbase.namequeues.request.NamedQueueGetRequest;
+import org.apache.hadoop.hbase.namequeues.response.NamedQueueGetResponse;
+import org.apache.hadoop.hbase.util.Threads;
+
+/**
+ * NamedQueue recorder that maintains various named queues.
+ * The service uses LMAX Disruptor to save queue records which are then consumed by
+ * a queue and based on the ring buffer size, the available records are then fetched
+ * from the queue in thread-safe manner.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public final class NamedQueueRecorder {
+
+  private final Disruptor<RingBufferEnvelope> disruptor;
+  private final LogEventHandler logEventHandler;
+
+  private static NamedQueueRecorder namedQueueRecorder;
+  private static boolean isInit = false;
+  private static final Object LOCK = new Object();
+
+  /**
+   * Initialize disruptor with configurable ringbuffer size
+   */
+  private NamedQueueRecorder(Configuration conf) {
+
+    // This is the 'writer' -- a single threaded executor. This single thread consumes what is
+    // put on the ringbuffer.
+    final String hostingThreadName = Thread.currentThread().getName();
+
+    int eventCount = conf.getInt("hbase.namedqueue.ringbuffer.size", 1024);
+
+    // disruptor initialization with BlockingWaitStrategy
+    this.disruptor = new Disruptor<>(getEventFactory(), getEventCount(eventCount), Executors.
+      newSingleThreadExecutor(Threads.getNamedThreadFactory(hostingThreadName
+        + ".slowlog.append-pool")),
+      ProducerType.MULTI, new BlockingWaitStrategy());
+    this.disruptor.handleExceptionsWith(new DisruptorExceptionHandler());
+
+    // initialize ringbuffer event handler
+    this.logEventHandler = new LogEventHandler(conf);
+    this.disruptor.handleEventsWith(new LogEventHandler[]{this.logEventHandler});
+    this.disruptor.start();
+  }
+
+  private EventFactory<RingBufferEnvelope> getEventFactory() {
+    return new EventFactory<RingBufferEnvelope>() {
+      @Override
+      public RingBufferEnvelope newInstance() {
+        return new RingBufferEnvelope();
+      }
+    };
+  }
+
+  public static NamedQueueRecorder getInstance(Configuration conf) {
+    if (namedQueueRecorder != null) {
+      return namedQueueRecorder;
+    }
+    synchronized (LOCK) {
+      if (!isInit) {
+        namedQueueRecorder = new NamedQueueRecorder(conf);
+        isInit = true;
+      }
+    }
+    return namedQueueRecorder;
+  }
+
+  // must be power of 2 for disruptor ringbuffer
+  private int getEventCount(int eventCount) {
+    Preconditions.checkArgument(eventCount >= 0, "hbase.namedqueue.ringbuffer.size must be > 0");
+    int floor = Integer.highestOneBit(eventCount);
+    if (floor == eventCount) {
+      return floor;
+    }
+    // max capacity is 1 << 30
+    if (floor >= 1 << 29) {
+      return 1 << 30;
+    }
+    return floor << 1;
+  }
+
+  /**
+   * Retrieve in memory queue records from ringbuffer
+   *
+   * @param request namedQueue request with event type
+   * @return queue records from ringbuffer after filter (if applied)
+   */
+  public NamedQueueGetResponse getNamedQueueRecords(NamedQueueGetRequest request) {
+    return this.logEventHandler.getNamedQueueRecords(request);
+  }
+
+  /**
+   * clears queue records from ringbuffer
+   *
+   * @param namedQueueEvent type of queue to clear
+   * @return true if slow log payloads are cleaned up or
+   *   hbase.regionserver.slowlog.buffer.enabled is not set to true, false if failed to
+   *   clean up slow logs
+   */
+  public boolean clearNamedQueue(NamedQueuePayload.NamedQueueEvent namedQueueEvent) {
+    return this.logEventHandler.clearNamedQueue(namedQueueEvent);
+  }
+
+  /**
+   * Add various NamedQueue records to ringbuffer. Based on the type of the event (e.g slowLog),
+   * consumer of disruptor ringbuffer will have specific logic.
+   * This method is producer of disruptor ringbuffer which is initialized in NamedQueueRecorder
+   * constructor.
+   *
+   * @param namedQueuePayload namedQueue payload sent by client of ring buffer
+   *   service
+   */
+  public void addRecord(NamedQueuePayload namedQueuePayload) {
+    RingBuffer<RingBufferEnvelope> ringBuffer = this.disruptor.getRingBuffer();
+    long seqId = ringBuffer.next();
+    try {
+      ringBuffer.get(seqId).load(namedQueuePayload);
+    } finally {
+      ringBuffer.publish(seqId);
+    }
+  }
+
+  /**
+   * Add all in memory queue records to system table. The implementors can use system table
+   * or direct HDFS file or ZK as persistence system.
+   */
+  public void persistAll(NamedQueuePayload.NamedQueueEvent namedQueueEvent) {
+    if (this.logEventHandler != null) {
+      this.logEventHandler.persistAll(namedQueueEvent);
+    }
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/NamedQueueService.java

@@ -0,0 +1,69 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.namequeues.request.NamedQueueGetRequest;
+import org.apache.hadoop.hbase.namequeues.response.NamedQueueGetResponse;
+
+/**
+ * In-memory Queue service provider for multiple use-cases. Implementers should be
+ * registered in LogEventHandler
+ */
+@InterfaceAudience.Private
+public interface NamedQueueService {
+
+  /**
+   * Retrieve event type for NamedQueueService implementation.
+   *
+   * @return {@link NamedQueuePayload.NamedQueueEvent}
+   */
+  NamedQueuePayload.NamedQueueEvent getEvent();
+
+  /**
+   * This implementation is generic for consuming records from LMAX
+   * disruptor and inserts records to EvictingQueue which is maintained by each
+   * ringbuffer provider.
+   *
+   * @param namedQueuePayload namedQueue payload from disruptor ring buffer
+   */
+  void consumeEventFromDisruptor(NamedQueuePayload namedQueuePayload);
+
+  /**
+   * Cleans up queues maintained by services.
+   *
+   * @return true if slow log payloads are cleaned up, false otherwise
+   */
+  boolean clearNamedQueue();
+
+  /**
+   * Retrieve in memory queue records from ringbuffer
+   *
+   * @param request namedQueue request with event type
+   * @return queue records from ringbuffer after filter (if applied)
+   */
+  NamedQueueGetResponse getNamedQueueRecords(NamedQueueGetRequest request);
+
+  /**
+   * Add all in memory queue records to system table. The implementors can use system table
+   * or direct HDFS file or ZK as persistence system.
+   */
+  void persistAll();
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/RingBufferEnvelope.java

@@ -0,0 +1,56 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+
+
+/**
+ * An envelope to carry payload in the ring buffer that serves as online buffer
+ * to provide latest events
+ */
+@InterfaceAudience.Private
+final class RingBufferEnvelope {
+
+  private NamedQueuePayload namedQueuePayload;
+
+  /**
+   * Load the Envelope with NamedQueuePayload
+   *
+   * @param namedQueuePayload all details of rpc call that would be useful for ring buffer
+   *   consumers
+   */
+  public void load(NamedQueuePayload namedQueuePayload) {
+    this.namedQueuePayload = namedQueuePayload;
+  }
+
+  /**
+   * Retrieve current namedQueue payload {@link NamedQueuePayload} available on Envelope and
+   * free up the Envelope
+   *
+   * @return Retrieve rpc log details
+   */
+  public NamedQueuePayload getPayload() {
+    final NamedQueuePayload namedQueuePayload = this.namedQueuePayload;
+    this.namedQueuePayload = null;
+    return namedQueuePayload;
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/RpcLogDetails.java

@@ -0,0 +1,117 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import com.google.protobuf.Descriptors;
+import com.google.protobuf.Message;
+import org.apache.commons.lang.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+
+/**
+ * RpcCall details that would be passed on to ring buffer of slow log responses
+ */
+@InterfaceAudience.Private
+public class RpcLogDetails extends NamedQueuePayload {
+
+  public static final int SLOW_LOG_EVENT = 0;
+
+  private final Descriptors.MethodDescriptor methodDescriptor;
+  private final Message param;
+  private final String clientAddress;
+  private final long responseSize;
+  private final String className;
+  private final boolean isSlowLog;
+  private final boolean isLargeLog;
+  private final long receiveTime;
+  private final long startTime;
+  private final String userName;
+
+  public RpcLogDetails(Descriptors.MethodDescriptor methodDescriptor, Message param,
+      String clientAddress, long responseSize, String className, boolean isSlowLog,
+      boolean isLargeLog, long receiveTime, long startTime, String userName) {
+    super(SLOW_LOG_EVENT);
+    this.methodDescriptor = methodDescriptor;
+    this.param = param;
+    this.clientAddress = clientAddress;
+    this.responseSize = responseSize;
+    this.className = className;
+    this.isSlowLog = isSlowLog;
+    this.isLargeLog = isLargeLog;
+    this.receiveTime = receiveTime;
+    this.startTime = startTime;
+    this.userName = userName;
+  }
+
+  public Descriptors.MethodDescriptor getMethodDescriptor() {
+    return methodDescriptor;
+  }
+
+  public String getClientAddress() {
+    return clientAddress;
+  }
+
+  public long getResponseSize() {
+    return responseSize;
+  }
+
+  public String getClassName() {
+    return className;
+  }
+
+  public boolean isSlowLog() {
+    return isSlowLog;
+  }
+
+  public boolean isLargeLog() {
+    return isLargeLog;
+  }
+
+  public Message getParam() {
+    return param;
+  }
+
+  public long getReceiveTime() {
+    return receiveTime;
+  }
+
+  public long getStartTime() {
+    return startTime;
+  }
+
+  public String getUserName() {
+    return userName;
+  }
+
+  @Override
+  public String toString() {
+    return new ToStringBuilder(this)
+      .append("methodDescriptor", methodDescriptor)
+      .append("param", param)
+      .append("clientAddress", clientAddress)
+      .append("responseSize", responseSize)
+      .append("className", className)
+      .append("isSlowLog", isSlowLog)
+      .append("isLargeLog", isLargeLog)
+      .append("receiveTime", receiveTime)
+      .append("startTime", startTime)
+      .append("userName", userName)
+      .toString();
+  }
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/SlowLogPersistentService.java

@@ -0,0 +1,94 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.locks.ReentrantLock;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.namequeues.queue.EvictingQueue;
+import org.apache.hadoop.hbase.protobuf.generated.TooSlowLog;
+import org.apache.hadoop.hbase.slowlog.SlowLogTableAccessor;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Persistent service provider for Slow/LargeLog events
+ */
+@InterfaceAudience.Private
+public class SlowLogPersistentService {
+
+  private static final Logger LOG = LoggerFactory.getLogger(SlowLogPersistentService.class);
+
+  private static final ReentrantLock LOCK = new ReentrantLock();
+  private static final String SYS_TABLE_QUEUE_SIZE =
+    "hbase.regionserver.slowlog.systable.queue.size";
+  private static final int DEFAULT_SYS_TABLE_QUEUE_SIZE = 1000;
+  private static final int SYSTABLE_PUT_BATCH_SIZE = 100;
+
+  private final EvictingQueue<TooSlowLog.SlowLogPayload> queueForSysTable;
+
+  private final Configuration configuration;
+
+  public SlowLogPersistentService(final Configuration configuration) {
+    this.configuration = configuration;
+    int sysTableQueueSize =
+      configuration.getInt(SYS_TABLE_QUEUE_SIZE, DEFAULT_SYS_TABLE_QUEUE_SIZE);
+    queueForSysTable = EvictingQueue.create(sysTableQueueSize);
+  }
+
+  public void addToQueueForSysTable(TooSlowLog.SlowLogPayload slowLogPayload) {
+    queueForSysTable.add(slowLogPayload);
+  }
+
+  /**
+   * Poll from queueForSysTable and insert 100 records in hbase:slowlog table in single batch
+   */
+  public void addAllLogsToSysTable() {
+    if (queueForSysTable == null) {
+      LOG.trace("hbase.regionserver.slowlog.systable.enabled is turned off. Exiting.");
+      return;
+    }
+    if (LOCK.isLocked()) {
+      return;
+    }
+    LOCK.lock();
+    try {
+      List<TooSlowLog.SlowLogPayload> slowLogPayloads = new ArrayList<>();
+      int i = 0;
+      while (!queueForSysTable.isEmpty()) {
+        slowLogPayloads.add(queueForSysTable.poll());
+        i++;
+        if (i == SYSTABLE_PUT_BATCH_SIZE) {
+          SlowLogTableAccessor.addSlowLogRecords(slowLogPayloads, this.configuration);
+          slowLogPayloads.clear();
+          i = 0;
+        }
+      }
+      if (slowLogPayloads.size() > 0) {
+        SlowLogTableAccessor.addSlowLogRecords(slowLogPayloads, this.configuration);
+      }
+    } finally {
+      LOCK.unlock();
+    }
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/SlowLogTableOpsChore.java

@@ -0,0 +1,63 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import org.apache.hadoop.hbase.ScheduledChore;
+import org.apache.hadoop.hbase.Stoppable;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Chore to insert multiple accumulated slow/large logs to hbase:slowlog system table
+ */
+@InterfaceAudience.Private
+public class SlowLogTableOpsChore extends ScheduledChore {
+
+  private static final Logger LOG = LoggerFactory.getLogger(SlowLogTableOpsChore.class);
+
+  private final NamedQueueRecorder namedQueueRecorder;
+
+  /**
+   * Chore Constructor
+   *
+   * @param stopper The stopper - When {@link Stoppable#isStopped()} is true, this chore will
+   *   cancel and cleanup
+   * @param period Period in millis with which this Chore repeats execution when scheduled
+   * @param namedQueueRecorder {@link NamedQueueRecorder} instance
+   */
+  public SlowLogTableOpsChore(final Stoppable stopper, final int period,
+      final NamedQueueRecorder namedQueueRecorder) {
+    super("SlowLogTableOpsChore", stopper, period);
+    this.namedQueueRecorder = namedQueueRecorder;
+  }
+
+  @Override
+  protected void chore() {
+    if (LOG.isTraceEnabled()) {
+      LOG.trace("SlowLog Table Ops Chore is starting up.");
+    }
+    namedQueueRecorder.persistAll(NamedQueuePayload.NamedQueueEvent.SLOW_LOG);
+    if (LOG.isTraceEnabled()) {
+      LOG.trace("SlowLog Table Ops Chore is closing.");
+    }
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/impl/BalancerDecisionQueueService.java

@@ -0,0 +1,144 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues.impl;
+
+import com.google.common.collect.Lists;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.client.BalancerDecision;
+import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer;
+import org.apache.hadoop.hbase.namequeues.BalancerDecisionDetails;
+import org.apache.hadoop.hbase.namequeues.NamedQueuePayload;
+import org.apache.hadoop.hbase.namequeues.NamedQueueService;
+import org.apache.hadoop.hbase.namequeues.queue.EvictingQueue;
+import org.apache.hadoop.hbase.namequeues.request.NamedQueueGetRequest;
+import org.apache.hadoop.hbase.namequeues.response.NamedQueueGetResponse;
+import org.apache.hadoop.hbase.protobuf.generated.RecentLogs;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * In-memory Queue service provider for Balancer Decision events
+ */
+@InterfaceAudience.Private
+public class BalancerDecisionQueueService implements NamedQueueService {
+
+  private static final Logger LOG = LoggerFactory.getLogger(BalancerDecisionQueueService.class);
+
+  private final boolean isBalancerDecisionRecording;
+
+  private static final String BALANCER_DECISION_QUEUE_SIZE =
+    "hbase.master.balancer.decision.queue.size";
+  private static final int DEFAULT_BALANCER_DECISION_QUEUE_SIZE = 250;
+
+  private static final int REGION_PLANS_THRESHOLD_PER_BALANCER = 15;
+
+  private final EvictingQueue<RecentLogs.BalancerDecision> balancerDecisionQueue;
+
+  public BalancerDecisionQueueService(Configuration conf) {
+    isBalancerDecisionRecording = conf.getBoolean(BaseLoadBalancer.BALANCER_DECISION_BUFFER_ENABLED,
+      BaseLoadBalancer.DEFAULT_BALANCER_DECISION_BUFFER_ENABLED);
+    if (!isBalancerDecisionRecording) {
+      balancerDecisionQueue = null;
+      return;
+    }
+    final int queueSize =
+      conf.getInt(BALANCER_DECISION_QUEUE_SIZE, DEFAULT_BALANCER_DECISION_QUEUE_SIZE);
+    balancerDecisionQueue = EvictingQueue.create(queueSize);
+  }
+
+  @Override
+  public NamedQueuePayload.NamedQueueEvent getEvent() {
+    return NamedQueuePayload.NamedQueueEvent.BALANCE_DECISION;
+  }
+
+  @Override
+  public void consumeEventFromDisruptor(NamedQueuePayload namedQueuePayload) {
+    if (!isBalancerDecisionRecording) {
+      return;
+    }
+    if (!(namedQueuePayload instanceof BalancerDecisionDetails)) {
+      LOG.warn(
+        "BalancerDecisionQueueService: NamedQueuePayload is not of type BalancerDecisionDetails.");
+      return;
+    }
+    BalancerDecisionDetails balancerDecisionDetails = (BalancerDecisionDetails) namedQueuePayload;
+    BalancerDecision balancerDecisionRecords =
+      balancerDecisionDetails.getBalancerDecision();
+    List<String> regionPlans = balancerDecisionRecords.getRegionPlans();
+    List<List<String>> regionPlansList;
+    if (regionPlans.size() > REGION_PLANS_THRESHOLD_PER_BALANCER) {
+      regionPlansList = Lists.partition(regionPlans, REGION_PLANS_THRESHOLD_PER_BALANCER);
+    } else {
+      regionPlansList = Collections.singletonList(regionPlans);
+    }
+    for (List<String> regionPlansPerBalancer : regionPlansList) {
+      RecentLogs.BalancerDecision balancerDecision = RecentLogs.BalancerDecision.newBuilder()
+        .setInitTotalCost(balancerDecisionRecords.getInitTotalCost())
+        .setInitialFunctionCosts(balancerDecisionRecords.getInitialFunctionCosts())
+        .setComputedTotalCost(balancerDecisionRecords.getComputedTotalCost())
+        .setFinalFunctionCosts(balancerDecisionRecords.getFinalFunctionCosts())
+        .setComputedSteps(balancerDecisionRecords.getComputedSteps())
+        .addAllRegionPlans(regionPlansPerBalancer)
+        .build();
+      balancerDecisionQueue.add(balancerDecision);
+    }
+  }
+
+  @Override
+  public boolean clearNamedQueue() {
+    if (!isBalancerDecisionRecording) {
+      return false;
+    }
+    LOG.debug("Received request to clean up balancer decision queue.");
+    balancerDecisionQueue.clear();
+    return true;
+  }
+
+  @Override
+  public NamedQueueGetResponse getNamedQueueRecords(NamedQueueGetRequest request) {
+    if (!isBalancerDecisionRecording) {
+      return null;
+    }
+    List<RecentLogs.BalancerDecision> balancerDecisions =
+      Arrays.asList(balancerDecisionQueue.toArray(new RecentLogs.BalancerDecision[0]));
+    // latest records should be displayed first, hence reverse order sorting
+    Collections.reverse(balancerDecisions);
+    int limit = balancerDecisions.size();
+    if (request.getBalancerDecisionsRequest().hasLimit()) {
+      limit = Math.min(request.getBalancerDecisionsRequest().getLimit(), balancerDecisions.size());
+    }
+    // filter limit if provided
+    balancerDecisions = balancerDecisions.subList(0, limit);
+    final NamedQueueGetResponse namedQueueGetResponse = new NamedQueueGetResponse();
+    namedQueueGetResponse.setNamedQueueEvent(BalancerDecisionDetails.BALANCER_DECISION_EVENT);
+    namedQueueGetResponse.setBalancerDecisions(balancerDecisions);
+    return namedQueueGetResponse;
+  }
+
+  @Override
+  public void persistAll() {
+    // no-op for now
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/impl/SlowLogQueueService.java

@@ -0,0 +1,268 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues.impl;
+
+import com.google.protobuf.Descriptors;
+import com.google.protobuf.Message;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import org.apache.commons.lang.StringUtils;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.client.SlowLogParams;
+import org.apache.hadoop.hbase.namequeues.LogHandlerUtils;
+import org.apache.hadoop.hbase.namequeues.NamedQueuePayload;
+import org.apache.hadoop.hbase.namequeues.NamedQueueService;
+import org.apache.hadoop.hbase.namequeues.RpcLogDetails;
+import org.apache.hadoop.hbase.namequeues.SlowLogPersistentService;
+import org.apache.hadoop.hbase.namequeues.queue.EvictingQueue;
+import org.apache.hadoop.hbase.namequeues.request.NamedQueueGetRequest;
+import org.apache.hadoop.hbase.namequeues.response.NamedQueueGetResponse;
+import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos;
+import org.apache.hadoop.hbase.protobuf.generated.ClientProtos;
+import org.apache.hadoop.hbase.protobuf.generated.TooSlowLog;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+/**
+ * In-memory Queue service provider for Slow/LargeLog events
+ */
+@InterfaceAudience.Private
+public class SlowLogQueueService implements NamedQueueService {
+
+  private static final Logger LOG = LoggerFactory.getLogger(SlowLogQueueService.class);
+
+  private static final String SLOW_LOG_RING_BUFFER_SIZE =
+    "hbase.regionserver.slowlog.ringbuffer.size";
+
+  private final boolean isOnlineLogProviderEnabled;
+  private final boolean isSlowLogTableEnabled;
+  private final SlowLogPersistentService slowLogPersistentService;
+  private final EvictingQueue<TooSlowLog.SlowLogPayload> slowLogQueue;
+
+  public SlowLogQueueService(Configuration conf) {
+    this.isOnlineLogProviderEnabled = conf.getBoolean(HConstants.SLOW_LOG_BUFFER_ENABLED_KEY,
+      HConstants.DEFAULT_ONLINE_LOG_PROVIDER_ENABLED);
+
+    if (!isOnlineLogProviderEnabled) {
+      this.isSlowLogTableEnabled = false;
+      this.slowLogPersistentService = null;
+      this.slowLogQueue = null;
+      return;
+    }
+
+    // Initialize SlowLog Queue
+    int slowLogQueueSize =
+      conf.getInt(SLOW_LOG_RING_BUFFER_SIZE, HConstants.DEFAULT_SLOW_LOG_RING_BUFFER_SIZE);
+
+    slowLogQueue = EvictingQueue.create(slowLogQueueSize);
+    this.isSlowLogTableEnabled = conf.getBoolean(HConstants.SLOW_LOG_SYS_TABLE_ENABLED_KEY,
+      HConstants.DEFAULT_SLOW_LOG_SYS_TABLE_ENABLED_KEY);
+    if (isSlowLogTableEnabled) {
+      slowLogPersistentService = new SlowLogPersistentService(conf);
+    } else {
+      slowLogPersistentService = null;
+    }
+  }
+
+  @Override
+  public NamedQueuePayload.NamedQueueEvent getEvent() {
+    return NamedQueuePayload.NamedQueueEvent.SLOW_LOG;
+  }
+
+  /**
+   * This implementation is specific to slowLog event. This consumes slowLog event from
+   * disruptor and inserts records to EvictingQueue.
+   *
+   * @param namedQueuePayload namedQueue payload from disruptor ring buffer
+   */
+  @Override
+  public void consumeEventFromDisruptor(NamedQueuePayload namedQueuePayload) {
+    if (!isOnlineLogProviderEnabled) {
+      return;
+    }
+    if (!(namedQueuePayload instanceof RpcLogDetails)) {
+      LOG.warn("SlowLogQueueService: NamedQueuePayload is not of type RpcLogDetails.");
+      return;
+    }
+    final RpcLogDetails rpcLogDetails = (RpcLogDetails) namedQueuePayload;
+    final Descriptors.MethodDescriptor methodDescriptor = rpcLogDetails.getMethodDescriptor();
+    final String clientAddress = rpcLogDetails.getClientAddress();
+    final long responseSize = rpcLogDetails.getResponseSize();
+    final String className = rpcLogDetails.getClassName();
+    final TooSlowLog.SlowLogPayload.Type type = getLogType(rpcLogDetails);
+    if (type == null) {
+      return;
+    }
+    Message param = rpcLogDetails.getParam();
+    long receiveTime = rpcLogDetails.getReceiveTime();
+    long startTime = rpcLogDetails.getStartTime();
+    long endTime = System.currentTimeMillis();
+    int processingTime = (int) (endTime - startTime);
+    int qTime = (int) (startTime - receiveTime);
+    final SlowLogParams slowLogParams = ProtobufUtil.getSlowLogParams(param);
+    int numGets = 0;
+    int numMutations = 0;
+    int numServiceCalls = 0;
+    if (param instanceof ClientProtos.MultiRequest) {
+      ClientProtos.MultiRequest multi = (ClientProtos.MultiRequest) param;
+      for (ClientProtos.RegionAction regionAction : multi.getRegionActionList()) {
+        for (ClientProtos.Action action : regionAction.getActionList()) {
+          if (action.hasMutation()) {
+            numMutations++;
+          }
+          if (action.hasGet()) {
+            numGets++;
+          }
+          if (action.hasServiceCall()) {
+            numServiceCalls++;
+          }
+        }
+      }
+    }
+    final String userName =
+      rpcLogDetails.getUserName() != null ? rpcLogDetails.getUserName() : StringUtils.EMPTY;
+    final String methodDescriptorName =
+      methodDescriptor != null ? methodDescriptor.getName() : StringUtils.EMPTY;
+    TooSlowLog.SlowLogPayload slowLogPayload = TooSlowLog.SlowLogPayload.newBuilder()
+      .setCallDetails(methodDescriptorName + "(" + param.getClass().getName() + ")")
+      .setClientAddress(clientAddress)
+      .setMethodName(methodDescriptorName)
+      .setMultiGets(numGets)
+      .setMultiMutations(numMutations)
+      .setMultiServiceCalls(numServiceCalls)
+      .setParam(slowLogParams != null ? slowLogParams.getParams() : StringUtils.EMPTY)
+      .setProcessingTime(processingTime)
+      .setQueueTime(qTime)
+      .setRegionName(slowLogParams != null ? slowLogParams.getRegionName() : StringUtils.EMPTY)
+      .setResponseSize(responseSize)
+      .setServerClass(className)
+      .setStartTime(startTime)
+      .setType(type)
+      .setUserName(userName)
+      .build();
+    slowLogQueue.add(slowLogPayload);
+    if (isSlowLogTableEnabled) {
+      if (!slowLogPayload.getRegionName().startsWith("hbase:slowlog")) {
+        slowLogPersistentService.addToQueueForSysTable(slowLogPayload);
+      }
+    }
+  }
+
+  @Override
+  public boolean clearNamedQueue() {
+    if (!isOnlineLogProviderEnabled) {
+      return false;
+    }
+    LOG.debug("Received request to clean up online slowlog buffer.");
+    slowLogQueue.clear();
+    return true;
+  }
+
+  @Override
+  public NamedQueueGetResponse getNamedQueueRecords(NamedQueueGetRequest request) {
+    if (!isOnlineLogProviderEnabled) {
+      return null;
+    }
+    final AdminProtos.SlowLogResponseRequest slowLogResponseRequest =
+      request.getSlowLogResponseRequest();
+    final List<TooSlowLog.SlowLogPayload> slowLogPayloads;
+    if (AdminProtos.SlowLogResponseRequest.LogType.LARGE_LOG
+        .equals(slowLogResponseRequest.getLogType())) {
+      slowLogPayloads = getLargeLogPayloads(slowLogResponseRequest);
+    } else {
+      slowLogPayloads = getSlowLogPayloads(slowLogResponseRequest);
+    }
+    NamedQueueGetResponse response = new NamedQueueGetResponse();
+    response.setNamedQueueEvent(RpcLogDetails.SLOW_LOG_EVENT);
+    response.setSlowLogPayloads(slowLogPayloads);
+    return response;
+  }
+
+  private TooSlowLog.SlowLogPayload.Type getLogType(RpcLogDetails rpcCallDetails) {
+    final boolean isSlowLog = rpcCallDetails.isSlowLog();
+    final boolean isLargeLog = rpcCallDetails.isLargeLog();
+    final TooSlowLog.SlowLogPayload.Type type;
+    if (!isSlowLog && !isLargeLog) {
+      LOG.error("slowLog and largeLog both are false. Ignoring the event. rpcCallDetails: {}",
+        rpcCallDetails);
+      return null;
+    }
+    if (isSlowLog && isLargeLog) {
+      type = TooSlowLog.SlowLogPayload.Type.ALL;
+    } else if (isSlowLog) {
+      type = TooSlowLog.SlowLogPayload.Type.SLOW_LOG;
+    } else {
+      type = TooSlowLog.SlowLogPayload.Type.LARGE_LOG;
+    }
+    return type;
+  }
+
+  /**
+   * Add all slowLog events to system table. This is only for slowLog event's persistence on
+   * system table.
+   */
+  @Override
+  public void persistAll() {
+    if (!isOnlineLogProviderEnabled) {
+      return;
+    }
+    if (slowLogPersistentService != null) {
+      slowLogPersistentService.addAllLogsToSysTable();
+    }
+  }
+
+  private List<TooSlowLog.SlowLogPayload> getSlowLogPayloads(
+      final AdminProtos.SlowLogResponseRequest request) {
+    TooSlowLog.SlowLogPayload[] slowLogPayloads =
+      slowLogQueue.toArray(new TooSlowLog.SlowLogPayload[0]);
+    List<TooSlowLog.SlowLogPayload> slowLogPayloadList = new ArrayList<>();
+    for (TooSlowLog.SlowLogPayload slowLogPayload : slowLogPayloads) {
+      if (slowLogPayload.getType() == TooSlowLog.SlowLogPayload.Type.ALL
+        || slowLogPayload.getType() == TooSlowLog.SlowLogPayload.Type.SLOW_LOG) {
+        slowLogPayloadList.add(slowLogPayload);
+      }
+    }
+    // latest slow logs first, operator is interested in latest records from in-memory buffer
+    Collections.reverse(slowLogPayloadList);
+    return LogHandlerUtils.getFilteredLogs(request, slowLogPayloadList);
+  }
+
+  private List<TooSlowLog.SlowLogPayload> getLargeLogPayloads(
+      final AdminProtos.SlowLogResponseRequest request) {
+    TooSlowLog.SlowLogPayload[] slowLogPayloads =
+      slowLogQueue.toArray(new TooSlowLog.SlowLogPayload[0]);
+    List<TooSlowLog.SlowLogPayload> slowLogPayloadList = new ArrayList<>();
+    for (TooSlowLog.SlowLogPayload slowLogPayload : slowLogPayloads) {
+      if (slowLogPayload.getType() == TooSlowLog.SlowLogPayload.Type.ALL
+        || slowLogPayload.getType() == TooSlowLog.SlowLogPayload.Type.LARGE_LOG) {
+        slowLogPayloadList.add(slowLogPayload);
+      }
+    }
+    // latest large logs first, operator is interested in latest records from in-memory buffer
+    Collections.reverse(slowLogPayloadList);
+    return LogHandlerUtils.getFilteredLogs(request, slowLogPayloadList);
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/queue/EvictingQueue.java

@@ -0,0 +1,85 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues.queue;
+
+import com.google.common.base.Preconditions;
+import java.io.Serializable;
+import java.util.Queue;
+import java.util.concurrent.ArrayBlockingQueue;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+
+@InterfaceAudience.Private
+public final class EvictingQueue<E> implements Serializable {
+
+  private final Queue<E> delegate;
+  final int maxSize;
+  private static final long serialVersionUID = 0L;
+
+  private EvictingQueue(int maxSize) {
+    Preconditions.checkArgument(maxSize >= 0, "maxSize (%s) must >= 0", maxSize);
+    this.delegate = new ArrayBlockingQueue<>(maxSize);
+    this.maxSize = maxSize;
+  }
+
+  public static <E> EvictingQueue<E> create(int maxSize) {
+    return new EvictingQueue<>(maxSize);
+  }
+
+  public int remainingCapacity() {
+    return this.maxSize - this.delegate.size();
+  }
+
+  protected Queue<E> delegate() {
+    return this.delegate;
+  }
+
+  public boolean offer(E e) {
+    return this.add(e);
+  }
+
+  public boolean add(E e) {
+    Preconditions.checkNotNull(e);
+    if (this.maxSize == 0) {
+      return true;
+    } else {
+      if (this.delegate().size() == this.maxSize) {
+        this.delegate.remove();
+      }
+      this.delegate.add(e);
+      return true;
+    }
+  }
+
+  public <T> T[] toArray(T[] array) {
+    return this.delegate().toArray(array);
+  }
+
+  public void clear() {
+    this.delegate().clear();
+  }
+
+  public boolean isEmpty() {
+    return this.delegate().isEmpty();
+  }
+
+  public E poll() {
+    return this.delegate().poll();
+  }
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/request/NamedQueueGetRequest.java

@@ -0,0 +1,77 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues.request;
+
+import org.apache.commons.lang.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.namequeues.NamedQueuePayload;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos;
+import org.apache.hadoop.hbase.protobuf.generated.MasterProtos;
+
+/**
+ * Request object to be used by ring buffer use-cases. Clients get records by sending
+ * this request object.
+ * For each ring buffer use-case, add request payload to this class, client should set
+ * namedQueueEvent based on use-case.
+ * Protobuf does not support inheritance, hence we need to work with
+ */
+@InterfaceAudience.Private
+public class NamedQueueGetRequest {
+
+  private AdminProtos.SlowLogResponseRequest slowLogResponseRequest;
+  private NamedQueuePayload.NamedQueueEvent namedQueueEvent;
+  private MasterProtos.BalancerDecisionsRequest balancerDecisionsRequest;
+
+  public AdminProtos.SlowLogResponseRequest getSlowLogResponseRequest() {
+    return slowLogResponseRequest;
+  }
+
+  public void setSlowLogResponseRequest(
+      AdminProtos.SlowLogResponseRequest slowLogResponseRequest) {
+    this.slowLogResponseRequest = slowLogResponseRequest;
+  }
+
+  public MasterProtos.BalancerDecisionsRequest getBalancerDecisionsRequest() {
+    return balancerDecisionsRequest;
+  }
+
+  public void setBalancerDecisionsRequest(
+    MasterProtos.BalancerDecisionsRequest balancerDecisionsRequest) {
+    this.balancerDecisionsRequest = balancerDecisionsRequest;
+  }
+
+  public NamedQueuePayload.NamedQueueEvent getNamedQueueEvent() {
+    return namedQueueEvent;
+  }
+
+  public void setNamedQueueEvent(int eventOrdinal) {
+    this.namedQueueEvent = NamedQueuePayload.NamedQueueEvent.getEventByOrdinal(eventOrdinal);
+  }
+
+  @Override
+  public String toString() {
+    return new ToStringBuilder(this)
+      .append("slowLogResponseRequest", slowLogResponseRequest)
+      .append("namedQueueEvent", namedQueueEvent)
+      .append("balancerDecisionsRequest", balancerDecisionsRequest)
+      .toString();
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/namequeues/response/NamedQueueGetResponse.java

@@ -0,0 +1,72 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues.response;
+
+import java.util.List;
+import org.apache.commons.lang.builder.ToStringBuilder;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.namequeues.NamedQueuePayload;
+import org.apache.hadoop.hbase.protobuf.generated.RecentLogs;
+import org.apache.hadoop.hbase.protobuf.generated.TooSlowLog;
+
+/**
+ * Response object to be sent by namedQueue service back to caller
+ */
+@InterfaceAudience.Private
+public class NamedQueueGetResponse {
+
+  private List<TooSlowLog.SlowLogPayload> slowLogPayloads;
+  private List<RecentLogs.BalancerDecision> balancerDecisions;
+  private NamedQueuePayload.NamedQueueEvent namedQueueEvent;
+
+  public List<TooSlowLog.SlowLogPayload> getSlowLogPayloads() {
+    return slowLogPayloads;
+  }
+
+  public void setSlowLogPayloads(List<TooSlowLog.SlowLogPayload> slowLogPayloads) {
+    this.slowLogPayloads = slowLogPayloads;
+  }
+
+  public List<RecentLogs.BalancerDecision> getBalancerDecisions() {
+    return balancerDecisions;
+  }
+
+  public void setBalancerDecisions(List<RecentLogs.BalancerDecision> balancerDecisions) {
+    this.balancerDecisions = balancerDecisions;
+  }
+
+  public NamedQueuePayload.NamedQueueEvent getNamedQueueEvent() {
+    return namedQueueEvent;
+  }
+
+  public void setNamedQueueEvent(int eventOrdinal) {
+    this.namedQueueEvent = NamedQueuePayload.NamedQueueEvent.getEventByOrdinal(eventOrdinal);
+  }
+
+  @Override
+  public String toString() {
+    return new ToStringBuilder(this)
+      .append("slowLogPayloads", slowLogPayloads)
+      .append("balancerDecisions", balancerDecisions)
+      .append("namedQueueEvent", namedQueueEvent)
+      .toString();
+  }
+
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java

@@ -125,6 +125,8 @@ import org.apache.hadoop.hbase.master.HMaster;
 import org.apache.hadoop.hbase.master.RegionState.State;
 import org.apache.hadoop.hbase.master.TableLockManager;
 import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer;
+import org.apache.hadoop.hbase.namequeues.NamedQueueRecorder;
+import org.apache.hadoop.hbase.namequeues.SlowLogTableOpsChore;
 import org.apache.hadoop.hbase.procedure.RegionServerProcedureManagerHost;
 import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
 import org.apache.hadoop.hbase.protobuf.RequestConverter;
@@ -417,6 +419,8 @@ public class HRegionServer extends HasThread implements
   private final int operationTimeout;
   private final int shortOperationTimeout;
 
+  private SlowLogTableOpsChore slowLogTableOpsChore = null;
+
   private final RegionServerAccounting regionServerAccounting;
 
   // Cache configuration and block cache reference
@@ -528,6 +532,11 @@ public class HRegionServer extends HasThread implements
 
   private volatile ThroughputController flushThroughputController;
 
+  /**
+   * Provide online slow log responses from ringbuffer
+   */
+  private NamedQueueRecorder namedQueueRecorder = null;
+
   /**
    * Starts a HRegionServer at the default location.
    */
@@ -581,6 +590,8 @@ public class HRegionServer extends HasThread implements
     this.abortRequested = new AtomicBoolean(false);
     this.stopped = false;
 
+    initNamedQueueRecorder(conf);
+
     rpcServices = createRpcServices();
     if (this instanceof HMaster) {
       useThisHostnameInstead = conf.get(MASTER_HOSTNAME_KEY);
@@ -697,6 +708,24 @@ public class HRegionServer extends HasThread implements
     this.initLatch = latch;
   }
 
+  private void initNamedQueueRecorder(Configuration conf) {
+    if (!(this instanceof HMaster)) {
+      final boolean isOnlineLogProviderEnabled = conf.getBoolean(
+        HConstants.SLOW_LOG_BUFFER_ENABLED_KEY,
+        HConstants.DEFAULT_ONLINE_LOG_PROVIDER_ENABLED);
+      if (isOnlineLogProviderEnabled) {
+        this.namedQueueRecorder = NamedQueueRecorder.getInstance(this.conf);
+      }
+    } else {
+      final boolean isBalancerDecisionRecording = conf
+        .getBoolean(BaseLoadBalancer.BALANCER_DECISION_BUFFER_ENABLED,
+          BaseLoadBalancer.DEFAULT_BALANCER_DECISION_BUFFER_ENABLED);
+      if (isBalancerDecisionRecording) {
+        this.namedQueueRecorder = NamedQueueRecorder.getInstance(this.conf);
+      }
+    }
+  }
+
   /*
    * Returns true if configured hostname should be used
    */
@@ -927,6 +956,14 @@ public class HRegionServer extends HasThread implements
     this.periodicFlusher = new PeriodicMemstoreFlusher(this.flushCheckFrequency, this);
     this.leases = new Leases(this.threadWakeFrequency);
 
+    final boolean isSlowLogTableEnabled = conf.getBoolean(HConstants.SLOW_LOG_SYS_TABLE_ENABLED_KEY,
+      HConstants.DEFAULT_SLOW_LOG_SYS_TABLE_ENABLED_KEY);
+    if (isSlowLogTableEnabled) {
+      // default chore duration: 10 min
+      final int duration = conf.getInt("hbase.slowlog.systable.chore.duration", 10 * 60 * 1000);
+      slowLogTableOpsChore = new SlowLogTableOpsChore(this, duration, this.namedQueueRecorder);
+    }
+
     // Create the thread to clean the moved regions list
     movedRegionsCleaner = MovedRegionsCleaner.create(this);
 
@@ -1436,6 +1473,15 @@ public class HRegionServer extends HasThread implements
     }
   }
 
+  /**
+   * get NamedQueue Provider to add different logs to ringbuffer
+   *
+   * @return NamedQueueRecorder
+   */
+  public NamedQueueRecorder getNamedQueueRecorder() {
+    return this.namedQueueRecorder;
+  }
+
   /*
    * Run init. Sets up wal and starts up all server threads.
    *
@@ -1904,6 +1950,9 @@ public class HRegionServer extends HasThread implements
     if (this.movedRegionsCleaner != null) {
       choreService.scheduleChore(movedRegionsCleaner);
     }
+    if (this.slowLogTableOpsChore != null) {
+      choreService.scheduleChore(slowLogTableOpsChore);
+    }
 
     // Leases is not a Thread. Internally it runs a daemon thread. If it gets
     // an unhandled exception, it will just exit.
@@ -2357,6 +2406,7 @@ public class HRegionServer extends HasThread implements
       choreService.cancelChore(executorStatusChore);
       choreService.cancelChore(storefileRefresher);
       choreService.cancelChore(movedRegionsCleaner);
+      choreService.cancelChore(slowLogTableOpsChore);
       // clean up the remaining scheduled chores (in case we missed out any)
       choreService.shutdown();
     }

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java

@@ -30,6 +30,8 @@ import com.google.protobuf.TextFormat;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InterruptedIOException;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.net.BindException;
 import java.net.InetSocketAddress;
 import java.net.UnknownHostException;
@@ -103,11 +105,19 @@ import org.apache.hadoop.hbase.ipc.RpcServer.BlockingServiceAndInterface;
 import org.apache.hadoop.hbase.ipc.RpcServerInterface;
 import org.apache.hadoop.hbase.ipc.ServerNotRunningYetException;
 import org.apache.hadoop.hbase.ipc.ServerRpcController;
+import org.apache.hadoop.hbase.master.HMaster;
 import org.apache.hadoop.hbase.master.MasterRpcServices;
+import org.apache.hadoop.hbase.namequeues.NamedQueuePayload;
+import org.apache.hadoop.hbase.namequeues.NamedQueueRecorder;
+import org.apache.hadoop.hbase.namequeues.RpcLogDetails;
+import org.apache.hadoop.hbase.namequeues.request.NamedQueueGetRequest;
+import org.apache.hadoop.hbase.namequeues.response.NamedQueueGetResponse;
 import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
 import org.apache.hadoop.hbase.protobuf.RequestConverter;
 import org.apache.hadoop.hbase.protobuf.ResponseConverter;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.ClearSlowLogResponseRequest;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.ClearSlowLogResponses;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.CloseRegionRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.CloseRegionResponse;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.CompactRegionRequest;
@@ -134,6 +144,8 @@ import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.ReplicateWALEntryR
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.ReplicateWALEntryResponse;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.RollWALWriterRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.RollWALWriterResponse;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.SlowLogResponseRequest;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.SlowLogResponses;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.SplitRegionRequest;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.SplitRegionResponse;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.StopServerRequest;
@@ -168,6 +180,7 @@ import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.RegionActionResul
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ResultOrException;
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ScanRequest;
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ScanResponse;
+import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
 import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.NameBytesPair;
 import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.NameInt64Pair;
 import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.RegionInfo;
@@ -175,6 +188,7 @@ import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.RegionSpecifier;
 import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.RegionSpecifier.RegionSpecifierType;
 import org.apache.hadoop.hbase.protobuf.generated.MapReduceProtos.ScanMetrics;
 import org.apache.hadoop.hbase.protobuf.generated.RPCProtos.RequestHeader;
+import org.apache.hadoop.hbase.protobuf.generated.TooSlowLog.SlowLogPayload;
 import org.apache.hadoop.hbase.protobuf.generated.WALProtos.BulkLoadDescriptor;
 import org.apache.hadoop.hbase.protobuf.generated.WALProtos.CompactionDescriptor;
 import org.apache.hadoop.hbase.protobuf.generated.WALProtos.FlushDescriptor;
@@ -263,7 +277,7 @@ public class RSRpcServices implements HBaseRPCErrorHandler,
   final RpcServerInterface rpcServer;
   final InetSocketAddress isa;
 
-  private final HRegionServer regionServer;
+  protected final HRegionServer regionServer;
   private final long maxScannerResultSize;
 
   // The reference to the priority extraction function
@@ -1172,6 +1186,9 @@ public class RSRpcServices implements HBaseRPCErrorHandler,
           "' configuration property.", be.getCause() != null ? be.getCause() : be);
     }
 
+    if (!(rs instanceof HMaster)) {
+      rpcServer.setNamedQueueRecorder(rs.getNamedQueueRecorder());
+    }
     scannerLeaseTimeoutPeriod = rs.conf.getInt(
       HConstants.HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD,
       HConstants.DEFAULT_HBASE_CLIENT_SCANNER_TIMEOUT_PERIOD);
@@ -3326,4 +3343,68 @@ public class RSRpcServices implements HBaseRPCErrorHandler,
     }
     return UpdateConfigurationResponse.getDefaultInstance();
   }
+
+  private List<SlowLogPayload> getSlowLogPayloads(SlowLogResponseRequest request,
+    NamedQueueRecorder namedQueueRecorder) {
+    if (namedQueueRecorder == null) {
+      return Collections.emptyList();
+    }
+    List<SlowLogPayload> slowLogPayloads;
+    NamedQueueGetRequest namedQueueGetRequest = new NamedQueueGetRequest();
+    namedQueueGetRequest.setNamedQueueEvent(RpcLogDetails.SLOW_LOG_EVENT);
+    namedQueueGetRequest.setSlowLogResponseRequest(request);
+    NamedQueueGetResponse namedQueueGetResponse =
+      namedQueueRecorder.getNamedQueueRecords(namedQueueGetRequest);
+    slowLogPayloads = namedQueueGetResponse != null ?
+      namedQueueGetResponse.getSlowLogPayloads() : new ArrayList<SlowLogPayload>();
+    return slowLogPayloads;
+  }
+
+  @Override
+  @QosPriority(priority=HConstants.ADMIN_QOS)
+  public ClearSlowLogResponses clearSlowLogsResponses(RpcController controller,
+      ClearSlowLogResponseRequest request) throws ServiceException {
+    final NamedQueueRecorder namedQueueRecorder =
+      this.regionServer.getNamedQueueRecorder();
+    boolean slowLogsCleaned = false;
+    if (namedQueueRecorder != null) {
+      namedQueueRecorder.clearNamedQueue(NamedQueuePayload.NamedQueueEvent.SLOW_LOG);
+      slowLogsCleaned = true;
+    }
+    ClearSlowLogResponses clearSlowLogResponses = ClearSlowLogResponses.newBuilder()
+      .setIsCleaned(slowLogsCleaned)
+      .build();
+    return clearSlowLogResponses;
+  }
+
+  @Override
+  @QosPriority(priority = HConstants.ADMIN_QOS)
+  public HBaseProtos.LogEntry getLogEntries(RpcController controller,
+      HBaseProtos.LogRequest request) throws ServiceException {
+    try {
+      final String logClassName = request.getLogClassName();
+      Class<?> logClass = Class.forName(logClassName)
+        .asSubclass(Message.class);
+      Method method = logClass.getMethod("parseFrom", ByteString.class);
+      if (logClassName.contains("SlowLogResponseRequest")) {
+        SlowLogResponseRequest slowLogResponseRequest =
+          (SlowLogResponseRequest) method.invoke(null, request.getLogMessage());
+        final NamedQueueRecorder namedQueueRecorder =
+          this.regionServer.getNamedQueueRecorder();
+        final List<SlowLogPayload> slowLogPayloads =
+          getSlowLogPayloads(slowLogResponseRequest, namedQueueRecorder);
+        SlowLogResponses slowLogResponses = SlowLogResponses.newBuilder()
+          .addAllSlowLogPayloads(slowLogPayloads)
+          .build();
+        return HBaseProtos.LogEntry.newBuilder()
+          .setLogClassName(slowLogResponses.getClass().getName())
+          .setLogMessage(slowLogResponses.toByteString()).build();
+      }
+    } catch (ClassNotFoundException | NoSuchMethodException | IllegalAccessException
+      | InvocationTargetException e) {
+      LOG.error("Error while retrieving log entries.", e);
+      throw new ServiceException(e);
+    }
+    throw new ServiceException("Invalid request params");
+  }
 }

hbase-server/src/test/java/org/apache/hadoop/hbase/master/MockRegionServer.java

@@ -98,6 +98,7 @@ import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.MutateRequest;
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.MutateResponse;
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ScanRequest;
 import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ScanResponse;
+import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
 import org.apache.hadoop.hbase.protobuf.generated.RegionServerStatusProtos.RegionStateTransition.TransitionCode;
 import org.apache.hadoop.hbase.quotas.RegionServerQuotaManager;
 import org.apache.hadoop.hbase.regionserver.CompactionRequestor;
@@ -654,6 +655,18 @@ ClientProtos.ClientService.BlockingInterface, RegionServerServices {
     return null;
   }
 
+  @Override
+  public AdminProtos.ClearSlowLogResponses clearSlowLogsResponses(RpcController controller,
+    AdminProtos.ClearSlowLogResponseRequest request) throws ServiceException {
+    return null;
+  }
+
+  @Override
+  public HBaseProtos.LogEntry getLogEntries(RpcController controller,
+      HBaseProtos.LogRequest request) throws ServiceException {
+    return null;
+  }
+
   @Override
   public HeapMemoryManager getHeapMemoryManager() {
     return null;

hbase-server/src/test/java/org/apache/hadoop/hbase/master/balancer/TestBalancerDecision.java

@@ -0,0 +1,102 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.master.balancer;
+
+import java.util.List;
+import java.util.Map;
+
+import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.HRegionInfo;
+import org.apache.hadoop.hbase.ServerName;
+import org.apache.hadoop.hbase.client.LogEntry;
+import org.apache.hadoop.hbase.master.RegionPlan;
+import org.apache.hadoop.hbase.namequeues.BalancerDecisionDetails;
+import org.apache.hadoop.hbase.namequeues.request.NamedQueueGetRequest;
+import org.apache.hadoop.hbase.namequeues.response.NamedQueueGetResponse;
+import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
+import org.apache.hadoop.hbase.protobuf.generated.MasterProtos;
+import org.apache.hadoop.hbase.protobuf.generated.RecentLogs;
+import org.apache.hadoop.hbase.testclassification.MasterTests;
+import org.apache.hadoop.hbase.testclassification.MediumTests;
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+
+/**
+ * Test BalancerDecision ring buffer using namedQueue interface
+ */
+@Category({ MasterTests.class, MediumTests.class })
+public class TestBalancerDecision extends BalancerTestBase {
+
+  @Test
+  public void testBalancerDecisions() {
+    conf.setBoolean("hbase.master.balancer.decision.buffer.enabled", true);
+    loadBalancer.setConf(conf);
+    float minCost = conf.getFloat("hbase.master.balancer.stochastic.minCostNeedBalance", 0.05f);
+    conf.setFloat("hbase.master.balancer.stochastic.minCostNeedBalance", 1.0f);
+    try {
+      // Test with/without per table balancer.
+      boolean[] perTableBalancerConfigs = {true, false};
+      for (boolean isByTable : perTableBalancerConfigs) {
+        conf.setBoolean(HConstants.HBASE_MASTER_LOADBALANCE_BYTABLE, isByTable);
+        loadBalancer.setConf(conf);
+        for (int[] mockCluster : clusterStateMocks) {
+          Map<ServerName, List<HRegionInfo>> servers = mockClusterServers(mockCluster);
+          List<RegionPlan> plans = loadBalancer.balanceCluster(servers);
+          boolean emptyPlans = plans == null || plans.isEmpty();
+          Assert.assertTrue(emptyPlans || needsBalanceIdleRegion(mockCluster));
+        }
+      }
+      final NamedQueueGetRequest namedQueueGetRequest = new NamedQueueGetRequest();
+      namedQueueGetRequest.setNamedQueueEvent(BalancerDecisionDetails.BALANCER_DECISION_EVENT);
+      namedQueueGetRequest
+        .setBalancerDecisionsRequest(MasterProtos.BalancerDecisionsRequest.getDefaultInstance());
+      NamedQueueGetResponse namedQueueGetResponse =
+        loadBalancer.namedQueueRecorder.getNamedQueueRecords(namedQueueGetRequest);
+      List<RecentLogs.BalancerDecision> balancerDecisions =
+        namedQueueGetResponse.getBalancerDecisions();
+      MasterProtos.BalancerDecisionsResponse response =
+        MasterProtos.BalancerDecisionsResponse.newBuilder()
+          .addAllBalancerDecision(balancerDecisions)
+          .build();
+      List<LogEntry> balancerDecisionRecords =
+        ProtobufUtil.getBalancerDecisionEntries(response);
+      Assert.assertTrue(balancerDecisionRecords.size() > 160);
+    } finally {
+      // reset config
+      conf.unset(HConstants.HBASE_MASTER_LOADBALANCE_BYTABLE);
+      conf.setFloat("hbase.master.balancer.stochastic.minCostNeedBalance", minCost);
+      loadBalancer.setConf(conf);
+    }
+  }
+
+  private boolean needsBalanceIdleRegion(int[] clusters) {
+    boolean b1 = false;
+    boolean b2 = false;
+    for (int cluster : clusters) {
+      if (cluster > 1) {
+        b1 = true;
+      } else {
+        b2 = true;
+      }
+    }
+    return b1 && b2;
+  }
+
+}

hbase-server/src/test/java/org/apache/hadoop/hbase/namequeues/TestNamedQueueRecorder.java

@@ -0,0 +1,716 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import com.google.protobuf.ByteString;
+import com.google.protobuf.Message;
+import java.lang.reflect.Constructor;
+import java.util.ArrayList;
+import java.util.List;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.HBaseTestingUtility;
+import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.Waiter;
+import org.apache.hadoop.hbase.namequeues.request.NamedQueueGetRequest;
+import org.apache.hadoop.hbase.namequeues.response.NamedQueueGetResponse;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos;
+import org.apache.hadoop.hbase.protobuf.generated.ClientProtos;
+import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
+import org.apache.hadoop.hbase.protobuf.generated.TooSlowLog;
+import org.apache.hadoop.hbase.testclassification.MasterTests;
+import org.apache.hadoop.hbase.testclassification.MediumTests;
+import org.junit.Assert;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Tests for Online SlowLog Provider Service
+ */
+@Category({MasterTests.class, MediumTests.class})
+public class TestNamedQueueRecorder {
+
+  private static final Logger LOG = LoggerFactory.getLogger(TestNamedQueueRecorder.class);
+
+  private static final HBaseTestingUtility HBASE_TESTING_UTILITY = new HBaseTestingUtility();
+
+  private NamedQueueRecorder namedQueueRecorder;
+
+  private static int i = 0;
+
+  private static Configuration applySlowLogRecorderConf(int eventSize) {
+    Configuration conf = HBASE_TESTING_UTILITY.getConfiguration();
+    conf.setBoolean(HConstants.SLOW_LOG_BUFFER_ENABLED_KEY, true);
+    conf.setInt("hbase.regionserver.slowlog.ringbuffer.size", eventSize);
+    return conf;
+  }
+
+  /**
+   * confirm that for a ringbuffer of slow logs, payload on given index of buffer
+   * has expected elements
+   *
+   * @param i index of ringbuffer logs
+   * @param j data value that was put on index i
+   * @param slowLogPayloads list of payload retrieved from {@link NamedQueueRecorder}
+   * @return if actual values are as per expectations
+   */
+  private boolean confirmPayloadParams(int i, int j,
+      List<TooSlowLog.SlowLogPayload> slowLogPayloads) {
+    boolean isClientExpected = slowLogPayloads.get(i).getClientAddress().equals("client_" + j);
+    boolean isUserExpected = slowLogPayloads.get(i).getUserName().equals("userName_" + j);
+    boolean isClassExpected = slowLogPayloads.get(i).getServerClass().equals("class_" + j);
+    return isClassExpected && isClientExpected && isUserExpected;
+  }
+
+  @Test
+  public void testOnlieSlowLogConsumption() throws Exception{
+    Configuration conf = applySlowLogRecorderConf(8);
+    Constructor<NamedQueueRecorder> constructor =
+      NamedQueueRecorder.class.getDeclaredConstructor(Configuration.class);
+    constructor.setAccessible(true);
+    namedQueueRecorder = constructor.newInstance(conf);
+    final AdminProtos.SlowLogResponseRequest request =
+      AdminProtos.SlowLogResponseRequest.newBuilder().setLimit(15).build();
+    namedQueueRecorder.clearNamedQueue(NamedQueuePayload.NamedQueueEvent.SLOW_LOG);
+    Assert.assertEquals(getSlowLogPayloads(request).size(), 0);
+    LOG.debug("Initially ringbuffer of Slow Log records is empty");
+    int i = 0;
+    // add 5 records initially
+    for (; i < 5; i++) {
+      RpcLogDetails rpcLogDetails =
+        getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+    Assert.assertNotEquals(-1,
+      HBASE_TESTING_UTILITY.waitFor(3000, new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(request).size() == 5;
+        }
+      }));
+    List<TooSlowLog.SlowLogPayload> slowLogPayloads = getSlowLogPayloads(request);
+    Assert.assertTrue(confirmPayloadParams(0, 5, slowLogPayloads));
+    Assert.assertTrue(confirmPayloadParams(1, 4, slowLogPayloads));
+    Assert.assertTrue(confirmPayloadParams(2, 3, slowLogPayloads));
+    Assert.assertTrue(confirmPayloadParams(3, 2, slowLogPayloads));
+    Assert.assertTrue(confirmPayloadParams(4, 1, slowLogPayloads));
+    for (; i < 7; i++) {
+      RpcLogDetails rpcLogDetails =
+        getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(request).size() == 7;
+        }
+      }));
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          List<TooSlowLog.SlowLogPayload> slowLogPayloadsList =
+            TestNamedQueueRecorder.this.getSlowLogPayloads(request);
+          return slowLogPayloadsList.size() == 7 && TestNamedQueueRecorder.this
+            .confirmPayloadParams(0, 7, slowLogPayloadsList) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(5, 2, slowLogPayloadsList) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(6, 1, slowLogPayloadsList);
+        }
+      })
+    );
+    // add 3 more records
+    for (; i < 10; i++) {
+      RpcLogDetails rpcLogDetails =
+        getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(request).size() == 8;
+        }
+      }));
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          List<TooSlowLog.SlowLogPayload> slowLogPayloadsList =
+            TestNamedQueueRecorder.this.getSlowLogPayloads(request);
+          // confirm ringbuffer is full
+          return slowLogPayloadsList.size() == 8 && TestNamedQueueRecorder.this
+            .confirmPayloadParams(7, 3, slowLogPayloadsList) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(0, 10, slowLogPayloadsList) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(1, 9, slowLogPayloadsList);
+        }
+      })
+    );
+    // add 4 more records
+    for (; i < 14; i++) {
+      RpcLogDetails rpcLogDetails =
+        getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(request).size() == 8;
+        }
+      }));
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          List<TooSlowLog.SlowLogPayload> slowLogPayloadsList =
+            TestNamedQueueRecorder.this.getSlowLogPayloads(request);
+          return slowLogPayloadsList.size() == 8 && TestNamedQueueRecorder.this
+            .confirmPayloadParams(0, 14, slowLogPayloadsList) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(1, 13, slowLogPayloadsList) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(2, 12, slowLogPayloadsList) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(3, 11, slowLogPayloadsList);
+        }
+      })
+    );
+    final AdminProtos.SlowLogResponseRequest largeLogRequest =
+      AdminProtos.SlowLogResponseRequest.newBuilder()
+        .setLimit(15)
+        .setLogType(AdminProtos.SlowLogResponseRequest.LogType.LARGE_LOG)
+        .build();
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          List<TooSlowLog.SlowLogPayload> slowLogPayloadsList =
+            TestNamedQueueRecorder.this.getSlowLogPayloads(largeLogRequest);
+          return slowLogPayloadsList.size() == 8 && TestNamedQueueRecorder.this
+            .confirmPayloadParams(0, 14, slowLogPayloadsList) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(1, 13, slowLogPayloadsList) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(2, 12, slowLogPayloadsList) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(3, 11, slowLogPayloadsList);
+        }
+      })
+    );
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          boolean isRingBufferCleaned =
+            namedQueueRecorder.clearNamedQueue(NamedQueuePayload.NamedQueueEvent.SLOW_LOG);
+          LOG.debug("cleared the ringbuffer of Online Slow Log records");
+          List<TooSlowLog.SlowLogPayload> slowLogPayloadsList =
+            TestNamedQueueRecorder.this.getSlowLogPayloads(request);
+          return slowLogPayloadsList.size() == 0 && isRingBufferCleaned;
+        }
+      })
+    );
+  }
+
+  private List<TooSlowLog.SlowLogPayload> getSlowLogPayloads(
+      AdminProtos.SlowLogResponseRequest request) {
+    NamedQueueGetRequest namedQueueGetRequest = new NamedQueueGetRequest();
+    namedQueueGetRequest.setNamedQueueEvent(RpcLogDetails.SLOW_LOG_EVENT);
+    namedQueueGetRequest.setSlowLogResponseRequest(request);
+    NamedQueueGetResponse namedQueueGetResponse =
+      namedQueueRecorder.getNamedQueueRecords(namedQueueGetRequest);
+    return namedQueueGetResponse == null ? new ArrayList<TooSlowLog.SlowLogPayload>()
+      : namedQueueGetResponse.getSlowLogPayloads();
+  }
+
+  @Test
+  public void testOnlineSlowLogWithHighRecords() throws Exception {
+
+    Configuration conf = applySlowLogRecorderConf(14);
+    Constructor<NamedQueueRecorder> constructor =
+      NamedQueueRecorder.class.getDeclaredConstructor(Configuration.class);
+    constructor.setAccessible(true);
+    namedQueueRecorder = constructor.newInstance(conf);
+    final AdminProtos.SlowLogResponseRequest request =
+      AdminProtos.SlowLogResponseRequest.newBuilder().setLimit(14 * 11).build();
+
+    Assert.assertEquals(getSlowLogPayloads(request).size(), 0);
+    LOG.debug("Initially ringbuffer of Slow Log records is empty");
+
+    for (int i = 0; i < 14 * 11; i++) {
+      RpcLogDetails rpcLogDetails =
+        getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+    LOG.debug("Added 14 * 11 records, ringbuffer should only provide latest 14 records");
+
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(request).size() == 14;
+        }
+      }));
+
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          List<TooSlowLog.SlowLogPayload> slowLogPayloads =
+            TestNamedQueueRecorder.this.getSlowLogPayloads(request);
+
+          // confirm strict order of slow log payloads
+          return slowLogPayloads.size() == 14 && TestNamedQueueRecorder.this
+            .confirmPayloadParams(0, 154, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(1, 153, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(2, 152, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(3, 151, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(4, 150, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(5, 149, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(6, 148, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(7, 147, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(8, 146, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(9, 145, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(10, 144, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(11, 143, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(12, 142, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(13, 141, slowLogPayloads);
+        }
+      })
+    );
+
+    boolean isRingBufferCleaned = namedQueueRecorder.clearNamedQueue(
+      NamedQueuePayload.NamedQueueEvent.SLOW_LOG);
+    Assert.assertTrue(isRingBufferCleaned);
+    LOG.debug("cleared the ringbuffer of Online Slow Log records");
+    List<TooSlowLog.SlowLogPayload> slowLogPayloads = getSlowLogPayloads(request);
+
+    // confirm ringbuffer is empty
+    Assert.assertEquals(slowLogPayloads.size(), 0);
+  }
+
+  @Test
+  public void testOnlineSlowLogWithDefaultDisableConfig() throws Exception {
+    Configuration conf = HBASE_TESTING_UTILITY.getConfiguration();
+    conf.unset(HConstants.SLOW_LOG_BUFFER_ENABLED_KEY);
+
+    Constructor<NamedQueueRecorder> constructor =
+      NamedQueueRecorder.class.getDeclaredConstructor(Configuration.class);
+    constructor.setAccessible(true);
+    namedQueueRecorder = constructor.newInstance(conf);
+    final AdminProtos.SlowLogResponseRequest request =
+      AdminProtos.SlowLogResponseRequest.newBuilder().build();
+    Assert.assertEquals(getSlowLogPayloads(request).size(), 0);
+    LOG.debug("Initially ringbuffer of Slow Log records is empty");
+    for (int i = 0; i < 300; i++) {
+      RpcLogDetails rpcLogDetails =
+        getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          List<TooSlowLog.SlowLogPayload> slowLogPayloads =
+            TestNamedQueueRecorder.this.getSlowLogPayloads(request);
+          return slowLogPayloads.size() == 0;
+        }
+      })
+    );
+
+  }
+
+  @Test
+  public void testOnlineSlowLogWithDisableConfig() throws Exception {
+    Configuration conf = HBASE_TESTING_UTILITY.getConfiguration();
+    conf.setBoolean(HConstants.SLOW_LOG_BUFFER_ENABLED_KEY, false);
+    Constructor<NamedQueueRecorder> constructor =
+      NamedQueueRecorder.class.getDeclaredConstructor(Configuration.class);
+    constructor.setAccessible(true);
+    namedQueueRecorder = constructor.newInstance(conf);
+
+    final AdminProtos.SlowLogResponseRequest request =
+      AdminProtos.SlowLogResponseRequest.newBuilder().build();
+    Assert.assertEquals(getSlowLogPayloads(request).size(), 0);
+    LOG.debug("Initially ringbuffer of Slow Log records is empty");
+    for (int i = 0; i < 300; i++) {
+      RpcLogDetails rpcLogDetails =
+        getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          List<TooSlowLog.SlowLogPayload> slowLogPayloads =
+            TestNamedQueueRecorder.this.getSlowLogPayloads(request);
+          return slowLogPayloads.size() == 0;
+        }
+      })
+    );
+    conf.setBoolean(HConstants.SLOW_LOG_BUFFER_ENABLED_KEY, true);
+  }
+
+  @Test
+  public void testSlowLogFilters() throws Exception {
+
+    Configuration conf = applySlowLogRecorderConf(30);
+    Constructor<NamedQueueRecorder> constructor =
+      NamedQueueRecorder.class.getDeclaredConstructor(Configuration.class);
+    constructor.setAccessible(true);
+    namedQueueRecorder = constructor.newInstance(conf);
+    final AdminProtos.SlowLogResponseRequest request =
+      AdminProtos.SlowLogResponseRequest.newBuilder()
+        .setLimit(15)
+        .setUserName("userName_87")
+        .build();
+
+    Assert.assertEquals(getSlowLogPayloads(request).size(), 0);
+
+    LOG.debug("Initially ringbuffer of Slow Log records is empty");
+
+    for (int i = 0; i < 100; i++) {
+      RpcLogDetails rpcLogDetails =
+        getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+    LOG.debug("Added 100 records, ringbuffer should only 1 record with matching filter");
+
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(request).size() == 1;
+        }
+      }));
+
+    final AdminProtos.SlowLogResponseRequest requestClient =
+      AdminProtos.SlowLogResponseRequest.newBuilder()
+        .setLimit(15)
+        .setClientAddress("client_85")
+        .build();
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(requestClient).size() == 1;
+        }
+      }));
+
+    final AdminProtos.SlowLogResponseRequest requestSlowLog =
+      AdminProtos.SlowLogResponseRequest.newBuilder()
+        .setLimit(15)
+        .build();
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(requestSlowLog).size() == 15;
+        }
+      }));
+  }
+
+  @Test
+  public void testConcurrentSlowLogEvents() throws Exception {
+
+    Configuration conf = applySlowLogRecorderConf(50000);
+    Constructor<NamedQueueRecorder> constructor =
+      NamedQueueRecorder.class.getDeclaredConstructor(Configuration.class);
+    constructor.setAccessible(true);
+    namedQueueRecorder = constructor.newInstance(conf);
+    final AdminProtos.SlowLogResponseRequest request =
+      AdminProtos.SlowLogResponseRequest.newBuilder().setLimit(500000).build();
+    final AdminProtos.SlowLogResponseRequest largeLogRequest =
+      AdminProtos.SlowLogResponseRequest.newBuilder()
+        .setLimit(500000)
+        .setLogType(AdminProtos.SlowLogResponseRequest.LogType.LARGE_LOG)
+        .build();
+    Assert.assertEquals(getSlowLogPayloads(request).size(), 0);
+    LOG.debug("Initially ringbuffer of Slow Log records is empty");
+
+    for (int j = 0; j < 1000; j++) {
+
+      new Thread(new Runnable() {
+        @Override public void run() {
+          for (int i = 0; i < 3500; i++) {
+            RpcLogDetails rpcLogDetails =
+              getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+            namedQueueRecorder.addRecord(rpcLogDetails);
+          }
+        }
+      }).start();
+
+    }
+
+    Thread.sleep(500);
+
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(
+      7000, new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(request).size() > 10000;
+        }
+      }));
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(
+      7000, new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(largeLogRequest).size() > 10000;
+        }
+      }));
+  }
+
+  @Test
+  public void testSlowLargeLogEvents() throws Exception {
+    Configuration conf = applySlowLogRecorderConf(28);
+    Constructor<NamedQueueRecorder> constructor =
+      NamedQueueRecorder.class.getDeclaredConstructor(Configuration.class);
+    constructor.setAccessible(true);
+    namedQueueRecorder = constructor.newInstance(conf);
+
+    final AdminProtos.SlowLogResponseRequest request =
+      AdminProtos.SlowLogResponseRequest.newBuilder().setLimit(14 * 11).build();
+
+    Assert.assertEquals(getSlowLogPayloads(request).size(), 0);
+    LOG.debug("Initially ringbuffer of Slow Log records is empty");
+
+    boolean isSlowLog;
+    boolean isLargeLog;
+    for (int i = 0; i < 14 * 11; i++) {
+      if (i % 2 == 0) {
+        isSlowLog = true;
+        isLargeLog = false;
+      } else {
+        isSlowLog = false;
+        isLargeLog = true;
+      }
+      RpcLogDetails rpcLogDetails =
+        getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1),
+          isSlowLog, isLargeLog);
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+    LOG.debug("Added 14 * 11 records, ringbuffer should only provide latest 14 records");
+
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(request).size() == 14;
+        }
+      }));
+
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          List<TooSlowLog.SlowLogPayload> slowLogPayloads =
+            TestNamedQueueRecorder.this.getSlowLogPayloads(request);
+
+          // confirm strict order of slow log payloads
+          return slowLogPayloads.size() == 14 && TestNamedQueueRecorder.this
+            .confirmPayloadParams(0, 153, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(1, 151, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(2, 149, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(3, 147, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(4, 145, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(5, 143, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(6, 141, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(7, 139, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(8, 137, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(9, 135, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(10, 133, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(11, 131, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(12, 129, slowLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(13, 127, slowLogPayloads);
+        }
+      })
+    );
+
+    final AdminProtos.SlowLogResponseRequest largeLogRequest =
+      AdminProtos.SlowLogResponseRequest.newBuilder()
+        .setLimit(14 * 11)
+        .setLogType(AdminProtos.SlowLogResponseRequest.LogType.LARGE_LOG)
+        .build();
+
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(largeLogRequest).size() == 14;
+        }
+      }));
+
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          List<TooSlowLog.SlowLogPayload> largeLogPayloads =
+            TestNamedQueueRecorder.this.getSlowLogPayloads(largeLogRequest);
+
+          // confirm strict order of slow log payloads
+          return largeLogPayloads.size() == 14 && TestNamedQueueRecorder.this
+            .confirmPayloadParams(0, 154, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(1, 152, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(2, 150, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(3, 148, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(4, 146, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(5, 144, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(6, 142, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(7, 140, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(8, 138, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(9, 136, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(10, 134, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(11, 132, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(12, 130, largeLogPayloads) && TestNamedQueueRecorder.this
+            .confirmPayloadParams(13, 128, largeLogPayloads);
+        }
+      })
+    );
+  }
+
+  @Test
+  public void testSlowLogMixedFilters() throws Exception {
+
+    Configuration conf = applySlowLogRecorderConf(30);
+    Constructor<NamedQueueRecorder> constructor =
+      NamedQueueRecorder.class.getDeclaredConstructor(Configuration.class);
+    constructor.setAccessible(true);
+    namedQueueRecorder = constructor.newInstance(conf);
+    final AdminProtos.SlowLogResponseRequest request =
+      AdminProtos.SlowLogResponseRequest.newBuilder()
+        .setLimit(15)
+        .setUserName("userName_87")
+        .setClientAddress("client_88")
+        .build();
+
+    Assert.assertEquals(getSlowLogPayloads(request).size(), 0);
+
+    for (int i = 0; i < 100; i++) {
+      RpcLogDetails rpcLogDetails =
+        getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(request).size() == 2;
+        }
+      }));
+
+    AdminProtos.SlowLogResponseRequest request2 = AdminProtos.SlowLogResponseRequest.newBuilder()
+      .setLimit(15)
+      .setUserName("userName_1")
+      .setClientAddress("client_2")
+      .build();
+    Assert.assertEquals(0, getSlowLogPayloads(request2).size());
+
+    AdminProtos.SlowLogResponseRequest request3 =
+      AdminProtos.SlowLogResponseRequest.newBuilder()
+        .setLimit(15)
+        .setUserName("userName_87")
+        .setClientAddress("client_88")
+        .setFilterByOperator(AdminProtos.SlowLogResponseRequest.FilterByOperator.AND)
+        .build();
+    Assert.assertEquals(0, getSlowLogPayloads(request3).size());
+
+    AdminProtos.SlowLogResponseRequest request4 =
+      AdminProtos.SlowLogResponseRequest.newBuilder()
+        .setLimit(15)
+        .setUserName("userName_87")
+        .setClientAddress("client_87")
+        .setFilterByOperator(AdminProtos.SlowLogResponseRequest.FilterByOperator.AND)
+        .build();
+    Assert.assertEquals(1, getSlowLogPayloads(request4).size());
+
+    AdminProtos.SlowLogResponseRequest request5 =
+      AdminProtos.SlowLogResponseRequest.newBuilder()
+        .setLimit(15)
+        .setUserName("userName_88")
+        .setClientAddress("client_89")
+        .setFilterByOperator(AdminProtos.SlowLogResponseRequest.FilterByOperator.OR)
+        .build();
+    Assert.assertEquals(2, getSlowLogPayloads(request5).size());
+
+    final AdminProtos.SlowLogResponseRequest requestSlowLog =
+      AdminProtos.SlowLogResponseRequest.newBuilder()
+        .setLimit(15)
+        .build();
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(3000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestNamedQueueRecorder.this.getSlowLogPayloads(requestSlowLog).size() == 15;
+        }
+      }));
+  }
+
+  static RpcLogDetails getRpcLogDetails(String userName, String clientAddress, String className) {
+    return new RpcLogDetails(null, getMessage(), clientAddress, 0, className, true, true, 0, 0,
+      userName);
+  }
+
+  private RpcLogDetails getRpcLogDetails(String userName, String clientAddress,
+      String className, boolean isSlowLog, boolean isLargeLog) {
+    return new RpcLogDetails(null, getMessage(), clientAddress, 0, className,
+      isSlowLog, isLargeLog, 0, 0, userName);
+  }
+
+  private static Message getMessage() {
+    i = (i + 1) % 3;
+    Message message = null;
+    switch (i) {
+      case 0: {
+        message = ClientProtos.ScanRequest.newBuilder()
+          .setRegion(HBaseProtos.RegionSpecifier.newBuilder()
+            .setValue(ByteString.copyFromUtf8("region1"))
+            .setType(HBaseProtos.RegionSpecifier.RegionSpecifierType.REGION_NAME)
+            .build())
+          .build();
+        break;
+      }
+      case 1: {
+        message = ClientProtos.MutateRequest.newBuilder()
+          .setRegion(HBaseProtos.RegionSpecifier.newBuilder()
+            .setValue(ByteString.copyFromUtf8("region2"))
+            .setType(HBaseProtos.RegionSpecifier.RegionSpecifierType.REGION_NAME))
+          .setMutation(ClientProtos.MutationProto.newBuilder()
+            .setRow(ByteString.copyFromUtf8("row123"))
+            .build())
+          .build();
+        break;
+      }
+      case 2: {
+        message = ClientProtos.GetRequest.newBuilder()
+          .setRegion(HBaseProtos.RegionSpecifier.newBuilder()
+            .setValue(ByteString.copyFromUtf8("region2"))
+            .setType(HBaseProtos.RegionSpecifier.RegionSpecifierType.REGION_NAME))
+          .setGet(ClientProtos.Get.newBuilder()
+            .setRow(ByteString.copyFromUtf8("row123"))
+            .build())
+          .build();
+        break;
+      }
+      default:
+        throw new RuntimeException("Not supposed to get here?");
+    }
+
+    return message;
+
+  }
+
+}

hbase-server/src/test/java/org/apache/hadoop/hbase/namequeues/TestSlowLogAccessor.java

@@ -0,0 +1,237 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.hbase.namequeues;
+
+import java.io.IOException;
+import java.lang.reflect.Field;
+import java.util.List;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.HBaseTestingUtility;
+import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.MetaTableAccessor;
+import org.apache.hadoop.hbase.Waiter;
+import org.apache.hadoop.hbase.client.Connection;
+import org.apache.hadoop.hbase.client.Result;
+import org.apache.hadoop.hbase.client.ResultScanner;
+import org.apache.hadoop.hbase.client.Scan;
+import org.apache.hadoop.hbase.client.Table;
+import org.apache.hadoop.hbase.namequeues.request.NamedQueueGetRequest;
+import org.apache.hadoop.hbase.namequeues.response.NamedQueueGetResponse;
+import org.apache.hadoop.hbase.protobuf.generated.AdminProtos;
+import org.apache.hadoop.hbase.protobuf.generated.TooSlowLog;
+import org.apache.hadoop.hbase.regionserver.HRegionServer;
+import org.apache.hadoop.hbase.slowlog.SlowLogTableAccessor;
+import org.apache.hadoop.hbase.testclassification.MasterTests;
+import org.apache.hadoop.hbase.testclassification.MediumTests;
+import org.junit.AfterClass;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Tests for SlowLog System Table
+ */
+@Category({ MasterTests.class, MediumTests.class })
+public class TestSlowLogAccessor {
+
+  private static final Logger LOG = LoggerFactory.getLogger(TestNamedQueueRecorder.class);
+
+  private static final HBaseTestingUtility HBASE_TESTING_UTILITY = new HBaseTestingUtility();
+
+  private NamedQueueRecorder namedQueueRecorder;
+
+  @BeforeClass
+  public static void setup() throws Exception {
+    try {
+      HBASE_TESTING_UTILITY.shutdownMiniHBaseCluster();
+    } catch (IOException e) {
+      LOG.debug("No worries.");
+    }
+    Configuration conf = HBASE_TESTING_UTILITY.getConfiguration();
+    conf.setBoolean(HConstants.SLOW_LOG_BUFFER_ENABLED_KEY, true);
+    conf.setBoolean(HConstants.SLOW_LOG_SYS_TABLE_ENABLED_KEY, true);
+    conf.setInt("hbase.slowlog.systable.chore.duration", 900);
+    conf.setInt("hbase.regionserver.slowlog.ringbuffer.size", 50000);
+    HBASE_TESTING_UTILITY.startMiniCluster();
+  }
+
+  @AfterClass
+  public static void teardown() throws Exception {
+    HBASE_TESTING_UTILITY.shutdownMiniHBaseCluster();
+  }
+
+  @Before
+  public void setUp() throws Exception {
+    HRegionServer hRegionServer = HBASE_TESTING_UTILITY.getMiniHBaseCluster().getRegionServer(0);
+    Field slowLogRecorder = HRegionServer.class.getDeclaredField("namedQueueRecorder");
+    slowLogRecorder.setAccessible(true);
+    this.namedQueueRecorder = (NamedQueueRecorder) slowLogRecorder.get(hRegionServer);
+  }
+
+  private List<TooSlowLog.SlowLogPayload> getSlowLogPayloads(
+      AdminProtos.SlowLogResponseRequest request) {
+    NamedQueueGetRequest namedQueueGetRequest = new NamedQueueGetRequest();
+    namedQueueGetRequest.setNamedQueueEvent(RpcLogDetails.SLOW_LOG_EVENT);
+    namedQueueGetRequest.setSlowLogResponseRequest(request);
+    NamedQueueGetResponse namedQueueGetResponse =
+      namedQueueRecorder.getNamedQueueRecords(namedQueueGetRequest);
+    return namedQueueGetResponse.getSlowLogPayloads();
+  }
+
+  @Test
+  public void testSlowLogRecords() throws Exception {
+
+    final AdminProtos.SlowLogResponseRequest request =
+      AdminProtos.SlowLogResponseRequest.newBuilder().setLimit(15).build();
+    namedQueueRecorder.clearNamedQueue(NamedQueuePayload.NamedQueueEvent.SLOW_LOG);
+    Assert.assertEquals(getSlowLogPayloads(request).size(), 0);
+
+    int i = 0;
+
+    final Connection connection = waitForSlowLogTableCreation();
+    // add 5 records initially
+    for (; i < 5; i++) {
+      RpcLogDetails rpcLogDetails = TestNamedQueueRecorder
+        .getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+
+    // add 2 more records
+    for (; i < 7; i++) {
+      RpcLogDetails rpcLogDetails = TestNamedQueueRecorder
+        .getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+
+    // add 3 more records
+    for (; i < 10; i++) {
+      RpcLogDetails rpcLogDetails = TestNamedQueueRecorder
+        .getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+
+    // add 4 more records
+    for (; i < 14; i++) {
+      RpcLogDetails rpcLogDetails = TestNamedQueueRecorder
+        .getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+      namedQueueRecorder.addRecord(rpcLogDetails);
+    }
+
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY
+      .waitFor(3000, new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestSlowLogAccessor.this.getSlowLogPayloads(request).size() == 14;
+        }
+      }));
+
+    Assert.assertNotEquals(-1,
+      HBASE_TESTING_UTILITY.waitFor(3000, new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          return TestSlowLogAccessor.this.getTableCount(connection) == 14;
+        }
+      }));
+  }
+
+  private int getTableCount(Connection connection) {
+    try (Table table = connection.getTable(SlowLogTableAccessor.SLOW_LOG_TABLE_NAME)) {
+      ResultScanner resultScanner = table.getScanner(new Scan().setReadType(Scan.ReadType.STREAM));
+      int count = 0;
+      for (Result result : resultScanner) {
+        ++count;
+      }
+      return count;
+    } catch (Exception e) {
+      return 0;
+    }
+  }
+
+  private Connection waitForSlowLogTableCreation() throws Exception {
+    final Connection connection =
+      HBASE_TESTING_UTILITY.getMiniHBaseCluster().getRegionServer(0).getConnection();
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(2000,
+      new Waiter.Predicate<Exception>() {
+        @Override public boolean evaluate() throws Exception {
+          try {
+            return MetaTableAccessor
+              .tableExists(connection, SlowLogTableAccessor.SLOW_LOG_TABLE_NAME);
+          } catch (IOException e) {
+            return false;
+          }
+        }
+      }));
+    return connection;
+  }
+
+  @Test
+  public void testHigherSlowLogs() throws Exception {
+    final Connection connection = waitForSlowLogTableCreation();
+
+    namedQueueRecorder.clearNamedQueue(NamedQueuePayload.NamedQueueEvent.SLOW_LOG);
+    final AdminProtos.SlowLogResponseRequest request =
+      AdminProtos.SlowLogResponseRequest.newBuilder().setLimit(500000).build();
+    Assert.assertEquals(getSlowLogPayloads(request).size(), 0);
+
+    for (int j = 0; j < 100; j++) {
+      new Thread(new Runnable() {
+        @Override
+        public void run() {
+          for (int i = 0; i < 350; i++) {
+            if (i == 300) {
+              try {
+                Thread.sleep(500);
+              } catch (InterruptedException e) {
+                LOG.warn("Interrupted.");
+              }
+            }
+            RpcLogDetails rpcLogDetails = TestNamedQueueRecorder
+              .getRpcLogDetails("userName_" + (i + 1), "client_" + (i + 1), "class_" + (i + 1));
+            namedQueueRecorder.addRecord(rpcLogDetails);
+          }
+        }
+      }).start();
+    }
+
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(8000,
+      new Waiter.Predicate<Exception>() {
+        @Override
+        public boolean evaluate() throws Exception {
+          int count = TestSlowLogAccessor.this.getSlowLogPayloads(request).size();
+          LOG.debug("RingBuffer records count: {}", count);
+          return count > 1500;
+        }
+      }));
+
+    Assert.assertNotEquals(-1, HBASE_TESTING_UTILITY.waitFor(11000,
+      new Waiter.Predicate<Exception>() {
+        @Override public boolean evaluate() throws Exception {
+          int count = TestSlowLogAccessor.this.getTableCount(connection);
+          LOG.debug("SlowLog Table records count: {}", count);
+          return count > 1500;
+        }
+      }));
+  }
+
+}

hbase-server/src/test/java/org/apache/hadoop/hbase/replication/regionserver/TestReplicator.java

@@ -35,6 +35,7 @@ import org.apache.hadoop.hbase.client.Put;
 import org.apache.hadoop.hbase.ipc.RpcServer;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService.BlockingInterface;
 import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.*;
+import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
 import org.apache.hadoop.hbase.replication.ReplicationPeerConfig;
 import org.apache.hadoop.hbase.replication.TestReplicationBase;
 import org.apache.hadoop.hbase.replication.regionserver.HBaseInterClusterReplicationEndpoint;
@@ -397,6 +398,18 @@ public class TestReplicator extends TestReplicationBase {
           UpdateConfigurationRequest request) throws ServiceException {
         return delegate.updateConfiguration(controller, request);
       }
+
+      @Override
+      public ClearSlowLogResponses clearSlowLogsResponses(RpcController controller,
+          ClearSlowLogResponseRequest request) throws ServiceException {
+        return delegate.clearSlowLogsResponses(controller, request);
+      }
+
+      @Override
+      public HBaseProtos.LogEntry getLogEntries(RpcController controller,
+          HBaseProtos.LogRequest request) throws ServiceException {
+        return delegate.getLogEntries(controller, request);
+      }
     }
 
     public class FailureInjectingReplicatorForTest extends ReplicatorForTest {

hbase-shell/src/main/ruby/hbase/admin.rb

@@ -1175,6 +1175,104 @@ module Hbase
       @admin.deleteNamespace(namespace_name)
     end
 
+    #----------------------------------------------------------------------------------------------
+    # Retrieve SlowLog Responses from RegionServers
+    def get_slowlog_responses(server_names, args, is_large_log = false)
+      unless server_names.is_a?(Array) || server_names.is_a?(String)
+        raise(ArgumentError,
+              "#{server_names.class} of #{server_names.inspect} is not of Array/String type")
+      end
+      if server_names == '*'
+        server_names = getServerNames([])
+      else
+        server_names_list = to_server_names(server_names)
+        server_names = getServerNames(server_names_list)
+      end
+      filter_params = get_filter_params(args)
+      (args.key? 'LIMIT') ? limit = args['LIMIT'] : limit = 10
+      is_large_log ? log_type = 'LARGE_LOG' : log_type = 'SLOW_LOG'
+      log_dest = org.apache.hadoop.hbase.client.ServerType::REGION_SERVER
+      server_names_set = java.util.HashSet.new(server_names)
+      slow_log_responses = @admin.getLogEntries(server_names_set, log_type, log_dest, limit,
+                                                filter_params)
+      slow_log_responses_arr = []
+      slow_log_responses.each do |slow_log_response|
+        slow_log_responses_arr << slow_log_response.toJsonPrettyPrint
+      end
+      slow_log_responses_arr
+    end
+
+    def get_filter_params(args)
+      filter_params = java.util.HashMap.new
+      if args.key? 'REGION_NAME'
+        region_name = args['REGION_NAME']
+        filter_params.put('regionName', region_name)
+      end
+      if args.key? 'TABLE_NAME'
+        table_name = args['TABLE_NAME']
+        filter_params.put('tableName', table_name)
+      end
+      if args.key? 'CLIENT_IP'
+        client_address = args['CLIENT_IP']
+        filter_params.put('clientAddress', client_address)
+      end
+      if args.key? 'USER'
+        user = args['USER']
+        filter_params.put('userName', user)
+      end
+      if args.key? 'FILTER_BY_OP'
+        filter_by_op = args['FILTER_BY_OP']
+        if filter_by_op != 'OR' && filter_by_op != 'AND'
+          raise(ArgumentError, 'FILTER_BY_OP should be either OR / AND')
+        end
+
+        filter_params.put('filterByOperator', 'AND') if filter_by_op == 'AND'
+      end
+      filter_params
+    end
+
+    #----------------------------------------------------------------------------------------------
+    # Clears SlowLog Responses from RegionServers
+    def clear_slowlog_responses(server_names)
+      unless server_names.nil? || server_names.is_a?(Array) || server_names.is_a?(String)
+        raise(ArgumentError,
+              "#{server_names.class} of #{server_names.inspect} is not of correct type")
+      end
+      if server_names.nil?
+        server_names = getServerNames([])
+      else
+        server_names_list = to_server_names(server_names)
+        server_names = getServerNames(server_names_list)
+      end
+      clear_log_responses = @admin.clearSlowLogResponses(java.util.HashSet.new(server_names))
+      clear_log_success_count = 0
+      clear_log_responses.each do |response|
+        if response
+          clear_log_success_count += 1
+        end
+      end
+      puts 'Cleared Slowlog responses from ' \
+           "#{clear_log_success_count}/#{clear_log_responses.size} RegionServers"
+    end
+
+    #----------------------------------------------------------------------------------------------
+    # Retrieve latest balancer decisions made by LoadBalancers
+    def get_balancer_decisions(args)
+      if args.key? 'LIMIT'
+        limit = args['LIMIT']
+      else
+        limit = 250
+      end
+      log_type = 'BALANCER_DECISION'
+      log_dest = org.apache.hadoop.hbase.client.ServerType::MASTER
+      balancer_decisions_responses = @admin.getLogEntries(nil, log_type, log_dest, limit, nil)
+      balancer_decisions_resp_arr = []
+      balancer_decisions_responses.each do |balancer_dec_resp|
+        balancer_decisions_resp_arr << balancer_dec_resp.toJsonPrettyPrint
+      end
+      balancer_decisions_resp_arr
+    end
+
     #----------------------------------------------------------------------------------------------
     # Get security capabilities
     def get_security_capabilities
@@ -1238,6 +1336,16 @@ module Hbase
       @admin.listDeadServers.to_a
     end
 
+    #----------------------------------------------------------------------------------------------
+    # Get list of server names
+    def to_server_names(server_names)
+      if server_names.is_a?(Array)
+        server_names
+      else
+        java.util.Arrays.asList(server_names)
+      end
+    end
+
     #----------------------------------------------------------------------------------------------
     # clear dead region servers
     def clear_deadservers(dead_servers)

hbase-shell/src/main/ruby/shell.rb

@@ -330,10 +330,14 @@ Shell.load_command_group(
     normalizer_switch
     normalizer_enabled
     is_in_maintenance_mode
+    clear_slowlog_responses
     close_region
     compact
     compaction_switch
     flush
+    get_balancer_decisions
+    get_slowlog_responses
+    get_largelog_responses
     major_compact
     move
     split

hbase-shell/src/main/ruby/shell/commands/clear_slowlog_responses.rb

@@ -0,0 +1,47 @@
+#
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements. See the NOTICE file distributed with this
+# work for additional information regarding copyright ownership. The ASF
+# licenses this file to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+# Clear slowlog responses maintained in memory by RegionServers
+
+module Shell
+  module Commands
+    # Clear slowlog responses
+    class ClearSlowlogResponses < Command
+      def help
+        <<-EOF
+Clears SlowLog Responses maintained by each or specific RegionServers.
+Specify array of server names for specific RS. A server name is
+the host, port plus startcode of a RegionServer.
+e.g.: host187.example.com,60020,1289493121758 (find servername in
+master ui or when you do detailed status in shell)
+
+Examples:
+
+  hbase> clear_slowlog_responses                                     => clears slowlog responses from all RS
+  hbase> clear_slowlog_responses ['SERVER_NAME1', 'SERVER_NAME2']    => clears slowlog responses from SERVER_NAME1,
+                                                                        SERVER_NAME2
+
+
+        EOF
+      end
+
+      def command(server_names = nil)
+        admin.clear_slowlog_responses(server_names)
+      end
+    end
+  end
+end

hbase-shell/src/main/ruby/shell/commands/get_balancer_decisions.rb

@@ -0,0 +1,47 @@
+#
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements. See the NOTICE file distributed with this
+# work for additional information regarding copyright ownership. The ASF
+# licenses this file to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+# Retrieve latest balancer decisions maintained in memory by HMaster
+
+module Shell
+  module Commands
+    # Retrieve latest large log responses
+    class GetBalancerDecisions < Command
+      def help
+        <<-EOF
+Retrieve latest balancer decisions made by LoadBalancers.
+
+Examples:
+
+  hbase> get_balancer_decisions                       => Retrieve recent balancer decisions with
+                                                         region plans
+  hbase> get_balancer_decisions LIMIT => 10           => Retrieve 10 most recent balancer decisions
+                                                         with region plans
+
+        EOF
+      end
+
+      def command(args = {})
+        raise 'Filter parameters are not Hash' unless args.is_a? Hash
+
+        balancer_decisions_resp_arr = admin.get_balancer_decisions(args)
+        puts 'Retrieved BalancerDecision Responses'
+        puts balancer_decisions_resp_arr
+      end
+    end
+  end
+end

hbase-shell/src/main/ruby/shell/commands/get_largelog_responses.rb

@@ -0,0 +1,98 @@
+#
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements. See the NOTICE file distributed with this
+# work for additional information regarding copyright ownership. The ASF
+# licenses this file to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+# Retrieve latest large log responses maintained in memory by RegionServers
+
+module Shell
+  module Commands
+    # Retrieve latest large log responses
+    class GetLargelogResponses < Command
+      def help
+        <<-EOF
+Retrieve latest LargeLog Responses maintained by each or specific RegionServers.
+Specify '*' to include all RS otherwise array of server names for specific
+RS. A server name is the host, port plus startcode of a RegionServer.
+e.g.: host187.example.com,60020,1289493121758 (find servername in
+master ui or when you do detailed status in shell)
+
+Provide optional filter parameters as Hash.
+Default Limit of each server for providing no of large log records is 10. User can specify
+more limit by 'LIMIT' param in case more than 10 records should be retrieved.
+
+Examples:
+
+  hbase> get_largelog_responses '*'                                 => get largelog responses from all RS
+  hbase> get_largelog_responses '*', {'LIMIT' => 50}                => get largelog responses from all RS
+                                                                      with 50 records limit (default limit: 10)
+  hbase> get_largelog_responses ['SERVER_NAME1', 'SERVER_NAME2']    => get largelog responses from SERVER_NAME1,
+                                                                      SERVER_NAME2
+  hbase> get_largelog_responses '*', {'REGION_NAME' => 'hbase:meta,,1'}
+                                                                   => get largelog responses only related to meta
+                                                                      region
+  hbase> get_largelog_responses '*', {'TABLE_NAME' => 't1'}         => get largelog responses only related to t1 table
+  hbase> get_largelog_responses '*', {'CLIENT_IP' => '192.162.1.40:60225', 'LIMIT' => 100}
+                                                                   => get largelog responses with given client
+                                                                      IP address and get 100 records limit
+                                                                      (default limit: 10)
+  hbase> get_largelog_responses '*', {'REGION_NAME' => 'hbase:meta,,1', 'TABLE_NAME' => 't1'}
+                                                                   => get largelog responses with given region name
+                                                                      or table name
+  hbase> get_largelog_responses '*', {'USER' => 'user_name', 'CLIENT_IP' => '192.162.1.40:60225'}
+                                                                   => get largelog responses that match either
+                                                                      provided client IP address or user name
+
+All of above queries with filters have default OR operation applied i.e. all
+records with any of the provided filters applied will be returned. However,
+we can also apply AND operator i.e. all records that match all (not any) of
+the provided filters should be returned.
+
+  hbase> get_largelog_responses '*', {'REGION_NAME' => 'hbase:meta,,1', 'TABLE_NAME' => 't1', 'FILTER_BY_OP' => 'AND'}
+                                                                   => get largelog responses with given region name
+                                                                      and table name, both should match
+
+  hbase> get_largelog_responses '*', {'REGION_NAME' => 'hbase:meta,,1', 'TABLE_NAME' => 't1', 'FILTER_BY_OP' => 'OR'}
+                                                                   => get largelog responses with given region name
+                                                                      or table name, any one can match
+
+  hbase> get_largelog_responses '*', {'TABLE_NAME' => 't1', 'CLIENT_IP' => '192.163.41.53:52781', 'FILTER_BY_OP' => 'AND'}
+                                                                   => get largelog responses with given region name
+                                                                      and client IP address, both should match
+
+Since OR is the default filter operator, without providing 'FILTER_BY_OP', query will have
+same result as providing 'FILTER_BY_OP' => 'OR'.
+
+Sometimes output can be long pretty printed json for user to scroll in
+a single screen and hence user might prefer
+redirecting output of get_largelog_responses to a file.
+
+Example:
+
+echo "get_largelog_responses '*'" | hbase shell > xyz.out 2>&1
+
+        EOF
+      end
+
+      def command(server_names, args = {})
+        raise 'Filter parameters are not Hash' unless args.is_a? Hash
+
+        large_log_responses_arr = admin.get_slowlog_responses(server_names, args, true)
+        puts 'Retrieved LargeLog Responses from RegionServers'
+        puts large_log_responses_arr
+      end
+    end
+  end
+end

hbase-shell/src/main/ruby/shell/commands/get_slowlog_responses.rb

@@ -0,0 +1,98 @@
+#
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements. See the NOTICE file distributed with this
+# work for additional information regarding copyright ownership. The ASF
+# licenses this file to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+# Retrieve latest slowlog responses maintained in memory by RegionServers
+
+module Shell
+  module Commands
+    # Retrieve latest slowlog responses
+    class GetSlowlogResponses < Command
+      def help
+        <<-EOF
+Retrieve latest SlowLog Responses maintained by each or specific RegionServers.
+Specify '*' to include all RS otherwise array of server names for specific
+RS. A server name is the host, port plus startcode of a RegionServer.
+e.g.: host187.example.com,60020,1289493121758 (find servername in
+master ui or when you do detailed status in shell)
+
+Provide optional filter parameters as Hash.
+Default Limit of each server for providing no of slow log records is 10. User can specify
+more limit by 'LIMIT' param in case more than 10 records should be retrieved.
+
+Examples:
+
+  hbase> get_slowlog_responses '*'                                 => get slowlog responses from all RS
+  hbase> get_slowlog_responses '*', {'LIMIT' => 50}                => get slowlog responses from all RS
+                                                                      with 50 records limit (default limit: 10)
+  hbase> get_slowlog_responses ['SERVER_NAME1', 'SERVER_NAME2']    => get slowlog responses from SERVER_NAME1,
+                                                                      SERVER_NAME2
+  hbase> get_slowlog_responses '*', {'REGION_NAME' => 'hbase:meta,,1'}
+                                                                   => get slowlog responses only related to meta
+                                                                      region
+  hbase> get_slowlog_responses '*', {'TABLE_NAME' => 't1'}         => get slowlog responses only related to t1 table
+  hbase> get_slowlog_responses '*', {'CLIENT_IP' => '192.162.1.40:60225', 'LIMIT' => 100}
+                                                                   => get slowlog responses with given client
+                                                                      IP address and get 100 records limit
+                                                                      (default limit: 10)
+  hbase> get_slowlog_responses '*', {'REGION_NAME' => 'hbase:meta,,1', 'TABLE_NAME' => 't1'}
+                                                                   => get slowlog responses with given region name
+                                                                      or table name
+  hbase> get_slowlog_responses '*', {'USER' => 'user_name', 'CLIENT_IP' => '192.162.1.40:60225'}
+                                                                   => get slowlog responses that match either
+                                                                      provided client IP address or user name
+
+All of above queries with filters have default OR operation applied i.e. all
+records with any of the provided filters applied will be returned. However,
+we can also apply AND operator i.e. all records that match all (not any) of
+the provided filters should be returned.
+
+  hbase> get_slowlog_responses '*', {'REGION_NAME' => 'hbase:meta,,1', 'TABLE_NAME' => 't1', 'FILTER_BY_OP' => 'AND'}
+                                                                   => get slowlog responses with given region name
+                                                                      and table name, both should match
+
+  hbase> get_slowlog_responses '*', {'REGION_NAME' => 'hbase:meta,,1', 'TABLE_NAME' => 't1', 'FILTER_BY_OP' => 'OR'}
+                                                                   => get slowlog responses with given region name
+                                                                      or table name, any one can match
+
+  hbase> get_slowlog_responses '*', {'TABLE_NAME' => 't1', 'CLIENT_IP' => '192.163.41.53:52781', 'FILTER_BY_OP' => 'AND'}
+                                                                   => get slowlog responses with given region name
+                                                                      and client IP address, both should match
+
+Since OR is the default filter operator, without providing 'FILTER_BY_OP', query will have
+same result as providing 'FILTER_BY_OP' => 'OR'.
+
+Sometimes output can be long pretty printed json for user to scroll in
+a single screen and hence user might prefer
+redirecting output of get_slowlog_responses to a file.
+
+Example:
+
+echo "get_slowlog_responses '*'" | hbase shell > xyz.out 2>&1
+
+        EOF
+      end
+
+      def command(server_names, args = {})
+        raise 'Filter parameters are not Hash' unless args.is_a? Hash
+
+        slow_log_responses_arr = admin.get_slowlog_responses(server_names, args)
+        puts 'Retrieved SlowLog Responses from RegionServers'
+        puts slow_log_responses_arr
+      end
+    end
+  end
+end

src/main/asciidoc/_chapters/hbase-default.adoc

@@ -2273,3 +2273,75 @@ The percent of region server RPC threads failed to abort RS.
 +
 .Default
 `false`
+
+
+
+[[hbase.regionserver.slowlog.ringbuffer.size]]
+*`hbase.regionserver.slowlog.ringbuffer.size`*::
++
+.Description
+
+      Default size of ringbuffer to be maintained by each RegionServer in order
+      to store online slowlog responses. This is an in-memory ring buffer of
+      requests that were judged to be too slow in addition to the responseTooSlow
+      logging. The in-memory representation would be complete.
+      For more details, please look into Doc Section:
+      <<slow_log_responses, slow_log_responses>>
+
+
++
+.Default
+`256`
+
+
+
+[[hbase.regionserver.slowlog.buffer.enabled]]
+*`hbase.regionserver.slowlog.buffer.enabled`*::
++
+.Description
+
+      Indicates whether RegionServers have ring buffer running for storing
+      Online Slow logs in FIFO manner with limited entries. The size of
+      the ring buffer is indicated by config: hbase.regionserver.slowlog.ringbuffer.size
+      The default value is false, turn this on and get latest slowlog
+      responses with complete data.
+      For more details, please look into Doc Section:
+      <<slow_log_responses, slow_log_responses>>
+
+
++
+.Default
+`false`
+
+
+[[hbase.regionserver.slowlog.systable.enabled]]
+*`hbase.regionserver.slowlog.systable.enabled`*::
++
+.Description
+
+      Should be enabled only if hbase.regionserver.slowlog.buffer.enabled is enabled.
+      If enabled (true), all slow/large RPC logs would be persisted to system table
+      hbase:slowlog (in addition to in-memory ring buffer at each RegionServer).
+      The records are stored in increasing order of time.
+      Operators can scan the table with various combination of ColumnValueFilter and
+      time range.
+      More details are provided in the doc section:
+      "Get Slow/Large Response Logs from System table hbase:slowlog"
+
++
+.Default
+`false`
+
+[[hbase.master.balancer.decision.buffer.enabled]]
+*`hbase.master.balancer.decision.buffer.enabled`*::
++
+.Description
+
+      Indicates whether active HMaster has ring buffer running for storing
+      balancer decisions in FIFO manner with limited entries. The size of
+      the ring buffer is indicated by config:
+      hbase.master.balancer.decision.queue.size
+
++
+.Default
+`false`

src/main/asciidoc/_chapters/ops_mgt.adoc

@@ -1472,6 +1472,187 @@ In the case that the call is not a client operation, that detailed fingerprint i
 
 This particular example, for example, would indicate that the likely cause of slowness is simply a very large (on the order of 100MB) multiput, as we can tell by the "vlen," or value length, fields of each put in the multiPut.
 
+
+[[slow_log_responses]]
+==== Get Slow Response Log from shell
+When an individual RPC exceeds a configurable time bound we log a complaint
+by way of the logging subsystem
+
+e.g.
+
+----
+2019-10-02 10:10:22,195 WARN [,queue=15,port=60020] ipc.RpcServer - (responseTooSlow):
+{"call":"Scan(org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ScanRequest)",
+"starttimems":1567203007549,
+"responsesize":6819737,
+"method":"Scan",
+"param":"region { type: REGION_NAME value: \"t1,\\000\\000\\215\\f)o\\\\\\024\\302\\220\\000\\000\\000\\000\\000\\001\\000\\000\\000\\000\\000\\006\\000\\000\\000\\000\\000\\005\\000\\000<TRUNCATED>",
+"processingtimems":28646,
+"client":"10.253.196.215:41116",
+"queuetimems":22453,
+"class":"HRegionServer"}
+----
+
+Unfortunately often the request parameters are truncated as per above Example.
+The truncation is unfortunate because it eliminates much of the utility of
+the warnings. For example, the region name, the start and end keys, and the
+filter hierarchy are all important clues for debugging performance problems
+caused by moderate to low selectivity queries or queries made at a high rate.
+
+HBASE-22978 introduces maintaining an in-memory ring buffer of requests that were judged to
+be too slow in addition to the responseTooSlow logging. The in-memory representation can be
+complete. There is some chance a high rate of requests will cause information on other
+interesting requests to be overwritten before it can be read. This is an acceptable trade off.
+
+In order to enable the in-memory ring buffer at RegionServers, we need to enable
+config:
+----
+hbase.regionserver.slowlog.buffer.enabled
+----
+
+One more config determines the size of the ring buffer:
+----
+hbase.regionserver.slowlog.ringbuffer.size
+----
+
+Check the config section for the detailed description.
+
+This config would be disabled by default. Turn it on and these shell commands
+would provide expected results from the ring-buffers.
+
+
+shell commands to retrieve slowlog responses from RegionServers:
+
+----
+Retrieve latest SlowLog Responses maintained by each or specific RegionServers.
+Specify '*' to include all RS otherwise array of server names for specific
+RS. A server name is the host, port plus startcode of a RegionServer.
+e.g.: host187.example.com,60020,1289493121758 (find servername in
+master ui or when you do detailed status in shell)
+
+Provide optional filter parameters as Hash.
+Default Limit of each server for providing no of slow log records is 10. User can specify
+more limit by 'LIMIT' param in case more than 10 records should be retrieved.
+
+Examples:
+
+  hbase> get_slowlog_responses '*'                                 => get slowlog responses from all RS
+  hbase> get_slowlog_responses '*', {'LIMIT' => 50}                => get slowlog responses from all RS
+                                                                      with 50 records limit (default limit: 10)
+  hbase> get_slowlog_responses ['SERVER_NAME1', 'SERVER_NAME2']    => get slowlog responses from SERVER_NAME1,
+                                                                      SERVER_NAME2
+  hbase> get_slowlog_responses '*', {'REGION_NAME' => 'hbase:meta,,1'}
+                                                                   => get slowlog responses only related to meta
+                                                                      region
+  hbase> get_slowlog_responses '*', {'TABLE_NAME' => 't1'}         => get slowlog responses only related to t1 table
+  hbase> get_slowlog_responses '*', {'CLIENT_IP' => '192.162.1.40:60225', 'LIMIT' => 100}
+                                                                   => get slowlog responses with given client
+                                                                      IP address and get 100 records limit
+                                                                      (default limit: 10)
+  hbase> get_slowlog_responses '*', {'REGION_NAME' => 'hbase:meta,,1', 'TABLE_NAME' => 't1'}
+                                                                   => get slowlog responses with given region name
+                                                                      or table name
+  hbase> get_slowlog_responses '*', {'USER' => 'user_name', 'CLIENT_IP' => '192.162.1.40:60225'}
+                                                                   => get slowlog responses that match either
+                                                                      provided client IP address or user name
+
+
+----
+
+All of above queries with filters have default OR operation applied i.e. all
+records with any of the provided filters applied will be returned. However,
+we can also apply AND operator i.e. all records that match all (not any) of
+the provided filters should be returned.
+
+----
+  hbase> get_slowlog_responses '*', {'REGION_NAME' => 'hbase:meta,,1', 'TABLE_NAME' => 't1', 'FILTER_BY_OP' => 'AND'}
+                                                                   => get slowlog responses with given region name
+                                                                      and table name, both should match
+
+  hbase> get_slowlog_responses '*', {'REGION_NAME' => 'hbase:meta,,1', 'TABLE_NAME' => 't1', 'FILTER_BY_OP' => 'OR'}
+                                                                   => get slowlog responses with given region name
+                                                                      or table name, any one can match
+
+  hbase> get_slowlog_responses '*', {'TABLE_NAME' => 't1', 'CLIENT_IP' => '192.163.41.53:52781', 'FILTER_BY_OP' => 'AND'}
+                                                                   => get slowlog responses with given region name
+                                                                      and client IP address, both should match
+
+----
+Since OR is the default filter operator, without providing 'FILTER_BY_OP', query will have
+same result as providing 'FILTER_BY_OP' => 'OR'.
+
+
+Sometimes output can be long pretty printed json for user to scroll in
+a single screen and hence user might prefer
+redirecting output of get_slowlog_responses to a file.
+
+Example:
+----
+echo "get_slowlog_responses '*'" | hbase shell > xyz.out 2>&1
+----
+
+Similar to slow RPC logs, client can also retrieve large RPC logs.
+Sometimes, slow logs important to debug perf issues turn out to be
+larger in size.
+
+----
+
+  hbase> get_largelog_responses '*'                                 => get largelog responses from all RS
+  hbase> get_largelog_responses '*', {'LIMIT' => 50}                => get largelog responses from all RS
+                                                                       with 50 records limit (default limit: 10)
+  hbase> get_largelog_responses ['SERVER_NAME1', 'SERVER_NAME2']    => get largelog responses from SERVER_NAME1,
+                                                                       SERVER_NAME2
+  hbase> get_largelog_responses '*', {'REGION_NAME' => 'hbase:meta,,1'}
+                                                                    => get largelog responses only related to meta
+                                                                       region
+  hbase> get_largelog_responses '*', {'TABLE_NAME' => 't1'}         => get largelog responses only related to t1 table
+  hbase> get_largelog_responses '*', {'CLIENT_IP' => '192.162.1.40:60225', 'LIMIT' => 100}
+                                                                    => get largelog responses with given client
+                                                                       IP address and get 100 records limit
+                                                                       (default limit: 10)
+  hbase> get_largelog_responses '*', {'REGION_NAME' => 'hbase:meta,,1', 'TABLE_NAME' => 't1'}
+                                                                    => get largelog responses with given region name
+                                                                       or table name
+  hbase> get_largelog_responses '*', {'USER' => 'user_name', 'CLIENT_IP' => '192.162.1.40:60225'}
+                                                                    => get largelog responses that match either
+                                                                       provided client IP address or user name
+
+  hbase> get_largelog_responses '*', {'REGION_NAME' => 'hbase:meta,,1', 'TABLE_NAME' => 't1', 'FILTER_BY_OP' => 'AND'}
+                                                                   => get largelog responses with given region name
+                                                                      and table name, both should match
+
+  hbase> get_largelog_responses '*', {'REGION_NAME' => 'hbase:meta,,1', 'TABLE_NAME' => 't1', 'FILTER_BY_OP' => 'OR'}
+                                                                   => get largelog responses with given region name
+                                                                      or table name, any one can match
+
+  hbase> get_largelog_responses '*', {'TABLE_NAME' => 't1', 'CLIENT_IP' => '192.163.41.53:52781', 'FILTER_BY_OP' => 'AND'}
+                                                                   => get largelog responses with given region name
+                                                                      and client IP address, both should match
+
+----
+
+
+shell command to clear slow/largelog responses from RegionServer:
+
+----
+Clears SlowLog Responses maintained by each or specific RegionServers.
+Specify array of server names for specific RS. A server name is
+the host, port plus startcode of a RegionServer.
+e.g.: host187.example.com,60020,1289493121758 (find servername in
+master ui or when you do detailed status in shell)
+
+Examples:
+
+  hbase> clear_slowlog_responses                                     => clears slowlog responses from all RS
+  hbase> clear_slowlog_responses ['SERVER_NAME1', 'SERVER_NAME2']    => clears slowlog responses from SERVER_NAME1,
+                                                                        SERVER_NAME2
+
+
+----
+
+include::slow_log_responses_from_systable.adoc[]
+
+
 === Block Cache Monitoring
 
 Starting with HBase 0.98, the HBase Web UI includes the ability to monitor and report on the performance of the block cache.

src/main/asciidoc/_chapters/slow_log_responses_from_systable.adoc

@@ -0,0 +1,118 @@
+////
+/**
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+////
+
+[[slow_log_responses_from_systable]]
+==== Get Slow/Large Response Logs from System table hbase:slowlog
+
+The above section provides details about Admin APIs:
+
+* get_slowlog_responses
+* get_largelog_responses
+* clear_slowlog_responses
+
+All of the above APIs access online in-memory ring buffers from
+individual RegionServers and accumulate logs from ring buffers to display
+to end user. However, since the logs are stored in memory, after RegionServer is
+restarted, all the objects held in memory of that RegionServer will be cleaned up
+and previous logs are lost. What if we want to persist all these logs forever?
+What if we want to store them in such a manner that operator can get all historical
+records with some filters? e.g get me all large/slow RPC logs that are triggered by
+user1 and are related to region:
+cluster_test,cccccccc,1589635796466.aa45e1571d533f5ed0bb31cdccaaf9cf. ?
+
+If we have a system table that stores such logs in increasing (not so strictly though)
+order of time, it can definitely help operators debug some historical events
+(scan, get, put, compaction, flush etc) with detailed inputs.
+
+Config which enabled system table to be created and store all log events is
+`hbase.regionserver.slowlog.systable.enabled`.
+
+The default value for this config is `false`. If provided `true`
+(Note: `hbase.regionserver.slowlog.buffer.enabled` should also be `true`),
+a cron job running in every RegionServer will persist the slow/large logs into
+table hbase:slowlog. By default cron job runs every 10 min. Duration can be configured
+with key: `hbase.slowlog.systable.chore.duration`. By default, RegionServer will
+store upto 1000(config key: `hbase.regionserver.slowlog.systable.queue.size`)
+slow/large logs in an internal queue and the chore will retrieve these logs
+from the queue and perform batch insertion in hbase:slowlog.
+
+hbase:slowlog has single ColumnFamily: `info`
+`info` contains multiple qualifiers which are the same attributes present as
+part of `get_slowlog_responses` API response.
+
+* info:call_details
+* info:client_address
+* info:method_name
+* info:param
+* info:processing_time
+* info:queue_time
+* info:region_name
+* info:response_size
+* info:server_class
+* info:start_time
+* info:type
+* info:username
+
+And example of 2 rows from hbase:slowlog scan result:
+[source]
+----
+
+ \x024\xC1\x03\xE9\x04\xF5@                                  column=info:call_details, timestamp=2020-05-16T14:58:14.211Z, value=Scan(org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos$ScanRequest)
+ \x024\xC1\x03\xE9\x04\xF5@                                  column=info:client_address, timestamp=2020-05-16T14:58:14.211Z, value=172.20.10.2:57347
+ \x024\xC1\x03\xE9\x04\xF5@                                  column=info:method_name, timestamp=2020-05-16T14:58:14.211Z, value=Scan
+ \x024\xC1\x03\xE9\x04\xF5@                                  column=info:param, timestamp=2020-05-16T14:58:14.211Z, value=region { type: REGION_NAME value: "hbase:meta,,1" } scan { column { family: "info" } attribute { name: "_isolationle
+                                                             vel_" value: "\x5C000" } start_row: "cluster_test,33333333,99999999999999" stop_row: "cluster_test,," time_range { from: 0 to: 9223372036854775807 } max_versions: 1 cache_blocks
+                                                             : true max_result_size: 2097152 reversed: true caching: 10 include_stop_row: true readType: PREAD } number_of_rows: 10 close_scanner: false client_handles_partials: true client_
+                                                             handles_heartbeats: true track_scan_metrics: false
+ \x024\xC1\x03\xE9\x04\xF5@                                  column=info:processing_time, timestamp=2020-05-16T14:58:14.211Z, value=18
+ \x024\xC1\x03\xE9\x04\xF5@                                  column=info:queue_time, timestamp=2020-05-16T14:58:14.211Z, value=0
+ \x024\xC1\x03\xE9\x04\xF5@                                  column=info:region_name, timestamp=2020-05-16T14:58:14.211Z, value=hbase:meta,,1
+ \x024\xC1\x03\xE9\x04\xF5@                                  column=info:response_size, timestamp=2020-05-16T14:58:14.211Z, value=1575
+ \x024\xC1\x03\xE9\x04\xF5@                                  column=info:server_class, timestamp=2020-05-16T14:58:14.211Z, value=HRegionServer
+ \x024\xC1\x03\xE9\x04\xF5@                                  column=info:start_time, timestamp=2020-05-16T14:58:14.211Z, value=1589640743732
+ \x024\xC1\x03\xE9\x04\xF5@                                  column=info:type, timestamp=2020-05-16T14:58:14.211Z, value=ALL
+ \x024\xC1\x03\xE9\x04\xF5@                                  column=info:username, timestamp=2020-05-16T14:58:14.211Z, value=user2
+ \x024\xC1\x06X\x81\xF6\xEC                                  column=info:call_details, timestamp=2020-05-16T14:59:58.764Z, value=Scan(org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos$ScanRequest)
+ \x024\xC1\x06X\x81\xF6\xEC                                  column=info:client_address, timestamp=2020-05-16T14:59:58.764Z, value=172.20.10.2:57348
+ \x024\xC1\x06X\x81\xF6\xEC                                  column=info:method_name, timestamp=2020-05-16T14:59:58.764Z, value=Scan
+ \x024\xC1\x06X\x81\xF6\xEC                                  column=info:param, timestamp=2020-05-16T14:59:58.764Z, value=region { type: REGION_NAME value: "cluster_test,cccccccc,1589635796466.aa45e1571d533f5ed0bb31cdccaaf9cf." } scan { a
+                                                             ttribute { name: "_isolationlevel_" value: "\x5C000" } start_row: "cccccccc" time_range { from: 0 to: 9223372036854775807 } max_versions: 1 cache_blocks: true max_result_size: 2
+                                                             097152 caching: 2147483647 include_stop_row: false } number_of_rows: 2147483647 close_scanner: false client_handles_partials: true client_handles_heartbeats: true track_scan_met
+                                                             rics: false
+ \x024\xC1\x06X\x81\xF6\xEC                                  column=info:processing_time, timestamp=2020-05-16T14:59:58.764Z, value=24
+ \x024\xC1\x06X\x81\xF6\xEC                                  column=info:queue_time, timestamp=2020-05-16T14:59:58.764Z, value=0
+ \x024\xC1\x06X\x81\xF6\xEC                                  column=info:region_name, timestamp=2020-05-16T14:59:58.764Z, value=cluster_test,cccccccc,1589635796466.aa45e1571d533f5ed0bb31cdccaaf9cf.
+ \x024\xC1\x06X\x81\xF6\xEC                                  column=info:response_size, timestamp=2020-05-16T14:59:58.764Z, value=211227
+ \x024\xC1\x06X\x81\xF6\xEC                                  column=info:server_class, timestamp=2020-05-16T14:59:58.764Z, value=HRegionServer
+ \x024\xC1\x06X\x81\xF6\xEC                                  column=info:start_time, timestamp=2020-05-16T14:59:58.764Z, value=1589640743932
+ \x024\xC1\x06X\x81\xF6\xEC                                  column=info:type, timestamp=2020-05-16T14:59:58.764Z, value=ALL
+ \x024\xC1\x06X\x81\xF6\xEC                                  column=info:username, timestamp=2020-05-16T14:59:58.764Z, value=user1
+----
+
+Operator can use ColumnValueFilter to filter records based on region_name, username,
+client_address etc.
+
+Time range based queries will also be very useful.
+Example:
+[source]
+----
+scan 'hbase:slowlog', { TIMERANGE => [1589621394000, 1589637999999] }
+----