HBASE-3130 [replication] ReplicationSource can't recover from session

expired on remote clusters (Chris Trezzo via JD)
   HBASE-4499  [replication] Source shouldn't update ZK if it didn't progress
               (Chris Trezzo via JD)


git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1177461 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -316,6 +316,8 @@ Release 0.92.0 - Unreleased
    HBASE-4455  Rolling restart RSs scenario, -ROOT-, .META. regions are lost in
                AssignmentManager (Ming Ma)
    HBASE-4513  NOTICES.txt refers to Facebook for Thrift
+   HBASE-3130  [replication] ReplicationSource can't recover from session
+               expired on remote clusters (Chris Trezzo via JD)
 
   TESTS
    HBASE-4450  test for number of blocks read: to serve as baseline for expected
@@ -558,6 +560,8 @@ Release 0.92.0 - Unreleased
                (David Revell)
    HBASE-4454  Add failsafe plugin to build and rename integration tests
                (Jesse Yates)
+   HBASE-4499  [replication] Source shouldn't update ZK if it didn't progress
+               (Chris Trezzo via JD)
 
   TASKS
    HBASE-3559  Move report of split to master OFF the heartbeat channel

src/main/java/org/apache/hadoop/hbase/replication/ReplicationPeer.java

@@ -19,21 +19,25 @@
  */
 package org.apache.hadoop.hbase.replication;
 
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicBoolean;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.Abortable;
 import org.apache.hadoop.hbase.ServerName;
 import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
 
 /**
  * This class acts as a wrapper for all the objects used to identify and
- * communicate with remote peers. Everything needs to be created for objects
- * of this class as it doesn't encapsulate any specific functionality e.g.
- * it's a container class.
+ * communicate with remote peers and is responsible for answering to expired
+ * sessions and re-establishing the ZK connections.
  */
-public class ReplicationPeer {
+public class ReplicationPeer implements Abortable {
+  private static final Log LOG = LogFactory.getLog(ReplicationPeer.class);
 
   private final String clusterKey;
   private final String id;
@@ -49,14 +53,13 @@ public class ReplicationPeer {
    * @param conf configuration object to this peer
    * @param key cluster key used to locate the peer
    * @param id string representation of this peer's identifier
-   * @param zkw zookeeper connection to the peer
    */
   public ReplicationPeer(Configuration conf, String key,
-      String id, ZooKeeperWatcher zkw) {
+      String id) throws IOException {
     this.conf = conf;
     this.clusterKey = key;
     this.id = id;
-    this.zkw = zkw;
+    this.reloadZkWatcher();
   }
 
   /**
@@ -116,4 +119,27 @@ public class ReplicationPeer {
   public Configuration getConfiguration() {
     return conf;
   }
+
+  @Override
+  public void abort(String why, Throwable e) {
+    LOG.warn("The ReplicationPeer coresponding to peer " + clusterKey
+        + " was aborted for the following reason(s):" + why, e);
+  }
+
+  /**
+   * Closes the current ZKW (if not null) and creates a new one
+   * @throws IOException If anything goes wrong connecting
+   */
+  public void reloadZkWatcher() throws IOException {
+    if (zkw != null) zkw.close();
+    zkw = new ZooKeeperWatcher(conf,
+        "connection to cluster: " + id, this);    
+  }
+
+  @Override
+  public boolean isAborted() {
+    // Currently the replication peer is never "Aborted", we just log when the
+    // abort method is called.
+    return false;
+  }
 }

src/main/java/org/apache/hadoop/hbase/replication/ReplicationZookeeper.java

@@ -21,6 +21,7 @@ package org.apache.hadoop.hbase.replication;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -43,6 +44,8 @@ import org.apache.hadoop.hbase.zookeeper.ZooKeeperListener;
 import org.apache.hadoop.hbase.zookeeper.ZooKeeperNodeTracker;
 import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
 import org.apache.zookeeper.KeeperException;
+import org.apache.zookeeper.KeeperException.ConnectionLossException;
+import org.apache.zookeeper.KeeperException.SessionExpiredException;
 
 /**
  * This class serves as a helper for all things related to zookeeper
@@ -210,8 +213,7 @@ public class ReplicationZookeeper {
    * @param peerClusterId (byte) the cluster to interrogate
    * @return addresses of all region servers
    */
-  public List<ServerName> getSlavesAddresses(String peerClusterId)
-      throws KeeperException {
+  public List<ServerName> getSlavesAddresses(String peerClusterId) {
     if (this.peerClusters.size() == 0) {
       return new ArrayList<ServerName>(0);
     }
@@ -219,7 +221,27 @@ public class ReplicationZookeeper {
     if (peer == null) {
       return new ArrayList<ServerName>(0);
     }
-    peer.setRegionServers(fetchSlavesAddresses(peer.getZkw()));
+    
+    List<ServerName> addresses;
+    try {
+      addresses = fetchSlavesAddresses(peer.getZkw());
+    } catch (KeeperException ke) {
+      if (ke instanceof ConnectionLossException
+          || ke instanceof SessionExpiredException) {
+        LOG.warn(
+            "Lost the ZooKeeper connection for peer " + peer.getClusterKey(),
+            ke);
+        try {
+          peer.reloadZkWatcher();
+        } catch(IOException io) {
+          LOG.warn(
+              "Creation of ZookeeperWatcher failed for peer "
+                  + peer.getClusterKey(), io);
+        }
+      }
+      addresses = Collections.emptyList();
+    }
+    peer.setRegionServers(addresses);
     return peer.getRegionServers();
   }
 
@@ -229,13 +251,9 @@ public class ReplicationZookeeper {
    * @return list of region server addresses or an empty list if the slave
    * is unavailable
    */
-  private List<ServerName> fetchSlavesAddresses(ZooKeeperWatcher zkw) {
-    try {
-      return listChildrenAndGetAsServerNames(zkw, zkw.rsZNode);
-    } catch (KeeperException e) {
-      LOG.warn("Cannot get peer's region server addresses", e);
-      return new ArrayList<ServerName>(0);
-    }
+  private List<ServerName> fetchSlavesAddresses(ZooKeeperWatcher zkw)
+    throws KeeperException {
+    return listChildrenAndGetAsServerNames(zkw, zkw.rsZNode);
   }
 
   /**
@@ -318,10 +336,8 @@ public class ReplicationZookeeper {
       return null;
     }
 
-    ZooKeeperWatcher zkw = new ZooKeeperWatcher(otherConf,
-        "connection to cluster: " + peerId, this.abortable);
     return new ReplicationPeer(otherConf, peerId,
-        otherClusterKey, zkw);
+        otherClusterKey);
   }
 
   /**

src/main/java/org/apache/hadoop/hbase/replication/regionserver/ReplicationSource.java

@@ -106,6 +106,8 @@ public class ReplicationSource extends Thread
   private HLog.Reader reader;
   // Current position in the log
   private long position = 0;
+  // Last position in the log that we sent to ZooKeeper
+  private long lastLoggedPosition = -1;
   // Path of the current log
   private volatile Path currentPath;
   private FileSystem fs;
@@ -210,10 +212,9 @@ public class ReplicationSource extends Thread
   /**
    * Select a number of peers at random using the ratio. Mininum 1.
    */
-  private void chooseSinks() throws KeeperException {
+  private void chooseSinks() {
     this.currentPeers.clear();
-    List<ServerName> addresses =
-        this.zkHelper.getSlavesAddresses(peerId);
+    List<ServerName> addresses = this.zkHelper.getSlavesAddresses(peerId);
     Set<ServerName> setOfAddr = new HashSet<ServerName>();
     int nbPeers = (int) (Math.ceil(addresses.size() * ratio));
     LOG.info("Getting " + nbPeers +
@@ -349,8 +350,11 @@ public class ReplicationSource extends Thread
       // wait a bit and retry.
       // But if we need to stop, don't bother sleeping
       if (this.isActive() && (gotIOE || currentNbEntries == 0)) {
-        this.manager.logPositionAndCleanOldLogs(this.currentPath,
-            this.peerClusterZnode, this.position, queueRecovered);
+        if (this.lastLoggedPosition != this.position) {
+          this.manager.logPositionAndCleanOldLogs(this.currentPath,
+              this.peerClusterZnode, this.position, queueRecovered);
+          this.lastLoggedPosition = this.position;
+        }
         if (sleepForRetries("Nothing to replicate", sleepMultiplier)) {
           sleepMultiplier++;
         }
@@ -435,8 +439,6 @@ public class ReplicationSource extends Thread
         Thread.sleep(this.sleepForRetries);
       } catch (InterruptedException e) {
         LOG.error("Interrupted while trying to connect to sinks", e);
-      } catch (KeeperException e) {
-        LOG.error("Error talking to zookeeper, retrying", e);
       }
     }
   }
@@ -592,8 +594,11 @@ public class ReplicationSource extends Thread
         HRegionInterface rrs = getRS();
         LOG.debug("Replicating " + currentNbEntries);
         rrs.replicateLogEntries(Arrays.copyOf(this.entriesArray, currentNbEntries));
-        this.manager.logPositionAndCleanOldLogs(this.currentPath,
-            this.peerClusterZnode, this.position, queueRecovered);
+        if (this.lastLoggedPosition != this.position) {
+          this.manager.logPositionAndCleanOldLogs(this.currentPath,
+              this.peerClusterZnode, this.position, queueRecovered);
+          this.lastLoggedPosition = this.position;
+        }
         this.totalReplicatedEdits += currentNbEntries;
         this.metrics.shippedBatchesRate.inc(1);
         this.metrics.shippedOpsRate.inc(
@@ -627,10 +632,7 @@ public class ReplicationSource extends Thread
           } while (this.isActive() && down );
         } catch (InterruptedException e) {
           LOG.debug("Interrupted while trying to contact the peer cluster");
-        } catch (KeeperException e) {
-          LOG.error("Error talking to zookeeper, retrying", e);
         }
-
       }
     }
   }

src/test/java/org/apache/hadoop/hbase/HBaseTestingUtility.java

@@ -1240,7 +1240,12 @@ public class HBaseTestingUtility {
   }
 
   public void expireSession(ZooKeeperWatcher nodeZK, Server server)
-  throws Exception {
+    throws Exception {
+    expireSession(nodeZK, server, false);
+  }
+
+  public void expireSession(ZooKeeperWatcher nodeZK, Server server,
+      boolean checkStatus) throws Exception {
     Configuration c = new Configuration(this.conf);
     String quorumServers = ZKConfig.getZKQuorumServersString(c);
     int sessionTimeout = 5 * 1000; // 5 seconds
@@ -1257,9 +1262,12 @@ public class HBaseTestingUtility {
 
     Thread.sleep(sleep);
 
-    new HTable(new Configuration(conf), HConstants.META_TABLE_NAME);
+    if (checkStatus) {
+      new HTable(new Configuration(conf), HConstants.META_TABLE_NAME);
+    }
   }
 
+
   /**
    * Get the HBase cluster.
    *

src/test/java/org/apache/hadoop/hbase/replication/TestReplicationPeer.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.replication;
+
+import junit.framework.Assert;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.HBaseConfiguration;
+import org.apache.hadoop.hbase.HBaseTestingUtility;
+import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
+import org.apache.zookeeper.KeeperException.SessionExpiredException;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class TestReplicationPeer {
+
+  private static final Log LOG = LogFactory.getLog(TestReplicationPeer.class);
+  private static HBaseTestingUtility utility;
+  private static Configuration conf;
+  private static ReplicationPeer rp;
+
+  @BeforeClass
+  public static void setUpBeforeClass() throws Exception {
+    conf = HBaseConfiguration.create();
+    utility = new HBaseTestingUtility(conf);
+    conf = utility.getConfiguration();
+    utility.startMiniZKCluster();
+
+    rp = new ReplicationPeer(conf, "clusterKey", "clusterId");
+  }
+
+  @Test(timeout=300000)
+  public void testResetZooKeeperSession() throws Exception {
+    ZooKeeperWatcher zkw = rp.getZkw();
+    zkw.getRecoverableZooKeeper().exists("/1/2", false);
+
+    LOG.info("Expiring ReplicationPeer ZooKeeper session.");
+    utility.expireSession(zkw, null, false);
+
+    try {
+      LOG.info("Attempting to use expired ReplicationPeer ZooKeeper session.");
+      // Trying to use the expired session to assert that it is indeed closed
+      zkw.getRecoverableZooKeeper().exists("/1/2", false);
+    } catch (SessionExpiredException k) {
+      rp.reloadZkWatcher();
+
+      zkw = rp.getZkw();
+
+      // Try to use the connection again
+      LOG.info("Attempting to use refreshed "
+          + "ReplicationPeer ZooKeeper session.");
+      zkw.getRecoverableZooKeeper().exists("/1/2", false);
+
+      return;
+    }
+
+    Assert.fail("ReplicationPeer ZooKeeper session was not properly expired.");
+  }
+
+}