HBASE-10367 RegionServer graceful stop / decommissioning

Signed-off-by: Jerry He <jerryjch@apache.org>

bin/draining_servers.rb

@@ -17,6 +17,8 @@
 #
 
 # Add or remove servers from draining mode via zookeeper
+# Deprecated in 2.0, and will be removed in 3.0. Use Admin decommission
+# API instead.
 
 require 'optparse'
 include Java

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

@@ -2425,22 +2425,30 @@ public interface Admin extends Abortable, Closeable {
   }
 
   /**
-   * Mark a region server as draining to prevent additional regions from getting assigned to it.
+   * Mark region server(s) as decommissioned to prevent additional regions from getting
-   * @param servers List of region servers to drain.
+   * assigned to them. Optionally unload the regions on the servers. If there are multiple servers
+   * to be decommissioned, decommissioning them at the same time can prevent wasteful region
+   * movements. Region unloading is asynchronous.
+   * @param servers The list of servers to decommission.
+   * @param offload True to offload the regions from the decommissioned servers
    */
-  void drainRegionServers(List<ServerName> servers) throws IOException;
+  void decommissionRegionServers(List<ServerName> servers, boolean offload) throws IOException;
 
   /**
-   * List region servers marked as draining to not get additional regions assigned to them.
+   * List region servers marked as decommissioned, which can not be assigned regions.
-   * @return List of draining region servers.
+   * @return List of decommissioned region servers.
    */
-  List<ServerName> listDrainingRegionServers() throws IOException;
+  List<ServerName> listDecommissionedRegionServers() throws IOException;
 
   /**
-   * Remove drain from a region server to allow additional regions assignments.
+   * Remove decommission marker from a region server to allow regions assignments.
-   * @param servers List of region servers to remove drain from.
+   * Load regions onto the server if a list of regions is given. Region loading is
+   * asynchronous.
+   * @param server The server to recommission.
+   * @param encodedRegionNames Regions to load onto the server.
    */
-  void removeDrainFromRegionServers(List<ServerName> servers) throws IOException;
+  void recommissionRegionServer(ServerName server, List<byte[]> encodedRegionNames)
+      throws IOException;
 
   /**
    * Find all table and column families that are replicated from this cluster

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

@@ -759,22 +759,29 @@ public interface AsyncAdmin {
   CompletableFuture<String> getLocks();
 
   /**
-   * Mark a region server as draining to prevent additional regions from getting assigned to it.
+   * Mark region server(s) as decommissioned to prevent additional regions from getting
-   * @param servers
+   * assigned to them. Optionally unload the regions on the servers. If there are multiple servers
+   * to be decommissioned, decommissioning them at the same time can prevent wasteful region
+   * movements. Region unloading is asynchronous.
+   * @param servers The list of servers to decommission.
+   * @param offload True to offload the regions from the decommissioned servers
    */
-  CompletableFuture<Void> drainRegionServers(List<ServerName> servers);
+  CompletableFuture<Void> decommissionRegionServers(List<ServerName> servers, boolean offload);
 
   /**
-   * List region servers marked as draining to not get additional regions assigned to them.
+   * List region servers marked as decommissioned, which can not be assigned regions.
-   * @return List of draining region servers wrapped by {@link CompletableFuture}
+   * @return List of decommissioned region servers wrapped by {@link CompletableFuture}
    */
-  CompletableFuture<List<ServerName>> listDrainingRegionServers();
+  CompletableFuture<List<ServerName>> listDecommissionedRegionServers();
 
   /**
-   * Remove drain from a region server to allow additional regions assignments.
+   * Remove decommission marker from a region server to allow regions assignments. Load regions onto
-   * @param servers List of region servers to remove drain from.
+   * the server if a list of regions is given. Region loading is asynchronous.
+   * @param server The server to recommission.
+   * @param encodedRegionNames Regions to load onto the server.
    */
-  CompletableFuture<Void> removeDrainFromRegionServers(List<ServerName> servers);
+  CompletableFuture<Void> recommissionRegionServer(ServerName server,
+      List<byte[]> encodedRegionNames);
 
   /**
    * @return cluster status wrapped by {@link CompletableFuture}

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

@@ -446,18 +446,20 @@ public class AsyncHBaseAdmin implements AsyncAdmin {
   }
 
   @Override
-  public CompletableFuture<Void> drainRegionServers(List<ServerName> servers) {
+  public CompletableFuture<Void> decommissionRegionServers(List<ServerName> servers,
-    return wrap(rawAdmin.drainRegionServers(servers));
+      boolean offload) {
+    return wrap(rawAdmin.decommissionRegionServers(servers, offload));
   }
 
   @Override
-  public CompletableFuture<List<ServerName>> listDrainingRegionServers() {
+  public CompletableFuture<List<ServerName>> listDecommissionedRegionServers() {
-    return wrap(rawAdmin.listDrainingRegionServers());
+    return wrap(rawAdmin.listDecommissionedRegionServers());
   }
 
   @Override
-  public CompletableFuture<Void> removeDrainFromRegionServers(List<ServerName> servers) {
+  public CompletableFuture<Void> recommissionRegionServer(ServerName server,
-    return wrap(rawAdmin.removeDrainFromRegionServers(servers));
+      List<byte[]> encodedRegionNames) {
+    return wrap(rawAdmin.recommissionRegionServer(server, encodedRegionNames));
   }
 
   @Override

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

@@ -89,18 +89,18 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.ClientProtos.ClientService.BlockingInterface;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DrainRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DecommissionRegionServersRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DrainRegionServersResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DecommissionRegionServersResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsBalancerEnabledRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsBalancerEnabledResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsNormalizerEnabledRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsNormalizerEnabledResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDrainingRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDecommissionedRegionServersRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDrainingRegionServersResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDecommissionedRegionServersResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.NormalizeRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.NormalizeResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RemoveDrainFromRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RecommissionRegionServerRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RemoveDrainFromRegionServersResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RecommissionRegionServerResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SecurityCapabilitiesRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SecurityCapabilitiesResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SetNormalizerRunningRequest;
@@ -1727,22 +1727,22 @@ class ConnectionImplementation implements ClusterConnection, Closeable {
       }
 
       @Override
-      public ListDrainingRegionServersResponse listDrainingRegionServers(RpcController controller,
+      public ListDecommissionedRegionServersResponse listDecommissionedRegionServers(RpcController controller,
-          ListDrainingRegionServersRequest request) throws ServiceException {
+          ListDecommissionedRegionServersRequest request) throws ServiceException {
-        return stub.listDrainingRegionServers(controller, request);
+        return stub.listDecommissionedRegionServers(controller, request);
       }
 
       @Override
-      public DrainRegionServersResponse drainRegionServers(RpcController controller,
+      public DecommissionRegionServersResponse decommissionRegionServers(RpcController controller,
-          DrainRegionServersRequest request) throws ServiceException {
+          DecommissionRegionServersRequest request) throws ServiceException {
-        return stub.drainRegionServers(controller, request);
+        return stub.decommissionRegionServers(controller, request);
       }
 
       @Override
-      public RemoveDrainFromRegionServersResponse removeDrainFromRegionServers(
+      public RecommissionRegionServerResponse recommissionRegionServer(
-          RpcController controller, RemoveDrainFromRegionServersRequest request)
+          RpcController controller, RecommissionRegionServerRequest request)
           throws ServiceException {
-        return stub.removeDrainFromRegionServers(controller, request);
+        return stub.recommissionRegionServer(controller, request);
       }
 
       @Override

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

@@ -171,7 +171,7 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsProcedur
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsSnapshotDoneRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsSnapshotDoneResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDeadServersRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDrainingRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDecommissionedRegionServersRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListNamespaceDescriptorsRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListTableDescriptorsByNamespaceRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListTableNamesByNamespaceRequest;
@@ -4030,27 +4030,28 @@ public class HBaseAdmin implements Admin {
   }
 
   @Override
-  public void drainRegionServers(List<ServerName> servers) throws IOException {
+  public void decommissionRegionServers(List<ServerName> servers, boolean offload)
+      throws IOException {
     executeCallable(new MasterCallable<Void>(getConnection(), getRpcControllerFactory()) {
       @Override
       public Void rpcCall() throws ServiceException {
-        master.drainRegionServers(getRpcController(),
+        master.decommissionRegionServers(getRpcController(),
-          RequestConverter.buildDrainRegionServersRequest(servers));
+          RequestConverter.buildDecommissionRegionServersRequest(servers, offload));
         return null;
       }
     });
   }
 
   @Override
-  public List<ServerName> listDrainingRegionServers() throws IOException {
+  public List<ServerName> listDecommissionedRegionServers() throws IOException {
     return executeCallable(new MasterCallable<List<ServerName>>(getConnection(),
               getRpcControllerFactory()) {
       @Override
       public List<ServerName> rpcCall() throws ServiceException {
-        ListDrainingRegionServersRequest req = ListDrainingRegionServersRequest.newBuilder().build();
+        ListDecommissionedRegionServersRequest req = ListDecommissionedRegionServersRequest.newBuilder().build();
         List<ServerName> servers = new ArrayList<>();
-        for (HBaseProtos.ServerName server : master.listDrainingRegionServers(null, req)
+        for (HBaseProtos.ServerName server : master
-            .getServerNameList()) {
+            .listDecommissionedRegionServers(getRpcController(), req).getServerNameList()) {
           servers.add(ProtobufUtil.toServerName(server));
         }
         return servers;
@@ -4059,11 +4060,13 @@ public class HBaseAdmin implements Admin {
   }
 
   @Override
-  public void removeDrainFromRegionServers(List<ServerName> servers) throws IOException {
+  public void recommissionRegionServer(ServerName server, List<byte[]> encodedRegionNames)
+      throws IOException {
     executeCallable(new MasterCallable<Void>(getConnection(), getRpcControllerFactory()) {
       @Override
       public Void rpcCall() throws ServiceException {
-        master.removeDrainFromRegionServers(getRpcController(), RequestConverter.buildRemoveDrainFromRegionServersRequest(servers));
+        master.recommissionRegionServer(getRpcController(),
+          RequestConverter.buildRecommissionRegionServerRequest(server, encodedRegionNames));
         return null;
       }
     });

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

@@ -126,6 +126,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateName
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateNamespaceResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateTableRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateTableResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DecommissionRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DecommissionRegionServersResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteColumnRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteColumnResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteNamespaceRequest;
@@ -136,8 +138,6 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteTabl
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteTableResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DisableTableRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DisableTableResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DrainRegionServersRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DrainRegionServersResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.EnableCatalogJanitorRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.EnableCatalogJanitorResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.EnableTableRequest;
@@ -180,8 +180,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsSplitOrM
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsSplitOrMergeEnabledResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDeadServersRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDeadServersResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDrainingRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDecommissionedRegionServersRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDrainingRegionServersResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDecommissionedRegionServersResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListNamespaceDescriptorsRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListNamespaceDescriptorsResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.MajorCompactionTimestampForRegionRequest;
@@ -200,8 +200,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.NormalizeR
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.NormalizeResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.OfflineRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.OfflineRegionResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RemoveDrainFromRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RecommissionRegionServerRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RemoveDrainFromRegionServersResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RecommissionRegionServerResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RestoreSnapshotRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RestoreSnapshotResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RunCatalogScanRequest;
@@ -1935,41 +1935,37 @@ public class RawAsyncHBaseAdmin implements AsyncAdmin {
   }
 
   @Override
-  public CompletableFuture<Void> drainRegionServers(List<ServerName> servers) {
+  public CompletableFuture<Void> decommissionRegionServers(List<ServerName> servers, boolean offload) {
-    return this
+    return this.<Void> newMasterCaller()
-        .<Void> newMasterCaller()
+        .action((controller, stub) -> this
-        .action(
+          .<DecommissionRegionServersRequest, DecommissionRegionServersResponse, Void> call(
-          (controller, stub) -> this
+            controller, stub, RequestConverter.buildDecommissionRegionServersRequest(servers, offload),
-              .<DrainRegionServersRequest, DrainRegionServersResponse, Void> call(controller, stub,
+            (s, c, req, done) -> s.decommissionRegionServers(c, req, done), resp -> null))
-                RequestConverter.buildDrainRegionServersRequest(servers),
+        .call();
-                (s, c, req, done) -> s.drainRegionServers(c, req, done), resp -> null)).call();
   }
 
   @Override
-  public CompletableFuture<List<ServerName>> listDrainingRegionServers() {
+  public CompletableFuture<List<ServerName>> listDecommissionedRegionServers() {
-    return this
+    return this.<List<ServerName>> newMasterCaller()
-        .<List<ServerName>> newMasterCaller()
+        .action((controller, stub) -> this
-        .action(
+          .<ListDecommissionedRegionServersRequest, ListDecommissionedRegionServersResponse,
-          (controller, stub) -> this
+            List<ServerName>> call(
-              .<ListDrainingRegionServersRequest, ListDrainingRegionServersResponse, List<ServerName>> call(
+              controller, stub, ListDecommissionedRegionServersRequest.newBuilder().build(),
-                controller,
+              (s, c, req, done) -> s.listDecommissionedRegionServers(c, req, done),
-                stub,
+              resp -> resp.getServerNameList().stream().map(ProtobufUtil::toServerName)
-                ListDrainingRegionServersRequest.newBuilder().build(),
+                  .collect(Collectors.toList())))
-                (s, c, req, done) -> s.listDrainingRegionServers(c, req, done),
+        .call();
-                resp -> resp.getServerNameList().stream().map(ProtobufUtil::toServerName)
-                    .collect(Collectors.toList()))).call();
   }
 
   @Override
-  public CompletableFuture<Void> removeDrainFromRegionServers(List<ServerName> servers) {
+  public CompletableFuture<Void> recommissionRegionServer(ServerName server,
-    return this
+      List<byte[]> encodedRegionNames) {
-        .<Void> newMasterCaller()
+    return this.<Void> newMasterCaller()
-        .action(
+        .action((controller, stub) -> this
-          (controller, stub) -> this
+          .<RecommissionRegionServerRequest, RecommissionRegionServerResponse, Void> call(controller,
-              .<RemoveDrainFromRegionServersRequest, RemoveDrainFromRegionServersResponse, Void> call(
+            stub, RequestConverter.buildRecommissionRegionServerRequest(server, encodedRegionNames),
-                controller, stub, RequestConverter
+            (s, c, req, done) -> s.recommissionRegionServer(c, req, done), resp -> null))
-                    .buildRemoveDrainFromRegionServersRequest(servers), (s, c, req, done) -> s
+        .call();
-                    .removeDrainFromRegionServers(c, req, done), resp -> null)).call();
   }
 
   /**

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

@@ -36,6 +36,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateName
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateNamespaceResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateTableRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateTableResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DecommissionRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DecommissionRegionServersResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteColumnRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteColumnResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteNamespaceRequest;
@@ -46,8 +48,6 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteTabl
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteTableResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DisableTableRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DisableTableResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DrainRegionServersRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DrainRegionServersResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.EnableCatalogJanitorRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.EnableCatalogJanitorResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.EnableTableRequest;
@@ -94,8 +94,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsSplitOrM
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsSplitOrMergeEnabledResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDeadServersRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDeadServersResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDrainingRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDecommissionedRegionServersRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDrainingRegionServersResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDecommissionedRegionServersResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListNamespaceDescriptorsRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListNamespaceDescriptorsResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListTableDescriptorsByNamespaceRequest;
@@ -120,8 +120,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.NormalizeR
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.NormalizeResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.OfflineRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.OfflineRegionResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RemoveDrainFromRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RecommissionRegionServerRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RemoveDrainFromRegionServersResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RecommissionRegionServerResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RestoreSnapshotRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RestoreSnapshotResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RunCatalogScanRequest;
@@ -257,9 +257,9 @@ public class ShortCircuitMasterConnection implements MasterKeepAliveConnection {
   }
 
   @Override
-  public RemoveDrainFromRegionServersResponse removeDrainFromRegionServers(RpcController controller,
+  public RecommissionRegionServerResponse recommissionRegionServer(RpcController controller,
-      RemoveDrainFromRegionServersRequest request) throws ServiceException {
+      RecommissionRegionServerRequest request) throws ServiceException {
-    return stub.removeDrainFromRegionServers(controller, request);
+    return stub.recommissionRegionServer(controller, request);
   }
 
   @Override
@@ -336,9 +336,9 @@ public class ShortCircuitMasterConnection implements MasterKeepAliveConnection {
   }
 
   @Override
-  public ListDrainingRegionServersResponse listDrainingRegionServers(RpcController controller,
+  public ListDecommissionedRegionServersResponse listDecommissionedRegionServers(RpcController controller,
-      ListDrainingRegionServersRequest request) throws ServiceException {
+      ListDecommissionedRegionServersRequest request) throws ServiceException {
-    return stub.listDrainingRegionServers(controller, request);
+    return stub.listDecommissionedRegionServers(controller, request);
   }
 
   @Override
@@ -493,9 +493,9 @@ public class ShortCircuitMasterConnection implements MasterKeepAliveConnection {
   }
 
   @Override
-  public DrainRegionServersResponse drainRegionServers(RpcController controller,
+  public DecommissionRegionServersResponse decommissionRegionServers(RpcController controller,
-      DrainRegionServersRequest request) throws ServiceException {
+      DecommissionRegionServersRequest request) throws ServiceException {
-    return stub.drainRegionServers(controller, request);
+    return stub.decommissionRegionServers(controller, request);
   }
 
   @Override

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

@@ -96,11 +96,11 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.BalanceReq
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ClearDeadServersRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateNamespaceRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateTableRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DecommissionRegionServersRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteColumnRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteNamespaceRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteTableRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DisableTableRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DrainRegionServersRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.EnableCatalogJanitorRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.EnableTableRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.GetClusterStatusRequest;
@@ -122,7 +122,7 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ModifyTabl
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.MoveRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.NormalizeRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.OfflineRegionRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RemoveDrainFromRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RecommissionRegionServerRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RunCatalogScanRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RunCleanerChoreRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SetBalancerRunningRequest;
@@ -1851,15 +1851,21 @@ public final class RequestConverter {
     return GET_QUOTA_STATES_REQUEST;
   }
 
-  public static DrainRegionServersRequest buildDrainRegionServersRequest(List<ServerName> servers) {
+  public static DecommissionRegionServersRequest
-    return DrainRegionServersRequest.newBuilder().addAllServerName(toProtoServerNames(servers))
+      buildDecommissionRegionServersRequest(List<ServerName> servers, boolean offload) {
-        .build();
+    return DecommissionRegionServersRequest.newBuilder()
+        .addAllServerName(toProtoServerNames(servers)).setOffload(offload).build();
   }
 
-  public static RemoveDrainFromRegionServersRequest buildRemoveDrainFromRegionServersRequest(
+  public static RecommissionRegionServerRequest
-      List<ServerName> servers) {
+      buildRecommissionRegionServerRequest(ServerName server, List<byte[]> encodedRegionNames) {
-    return RemoveDrainFromRegionServersRequest.newBuilder()
+    RecommissionRegionServerRequest.Builder builder = RecommissionRegionServerRequest.newBuilder();
-        .addAllServerName(toProtoServerNames(servers)).build();
+    if (encodedRegionNames != null) {
+      for (byte[] name : encodedRegionNames) {
+        builder.addRegion(buildRegionSpecifier(RegionSpecifierType.ENCODED_REGION_NAME, name));
+      }
+    }
+    return builder.setServerName(ProtobufUtil.toServerName(server)).build();
   }
 
   private static List<HBaseProtos.ServerName> toProtoServerNames(List<ServerName> servers) {

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

@@ -602,25 +602,27 @@ message SecurityCapabilitiesResponse {
   repeated Capability capabilities = 1;
 }
 
-message ListDrainingRegionServersRequest {
+message ListDecommissionedRegionServersRequest {
 }
 
-message ListDrainingRegionServersResponse {
+message ListDecommissionedRegionServersResponse {
- repeated ServerName server_name = 1;
+  repeated ServerName server_name = 1;
 }
 
-message DrainRegionServersRequest {
+message DecommissionRegionServersRequest {
- repeated ServerName server_name = 1;
+  repeated ServerName server_name = 1;
+  required bool offload = 2;
 }
 
-message DrainRegionServersResponse {
+message DecommissionRegionServersResponse {
 }
 
-message RemoveDrainFromRegionServersRequest {
+message RecommissionRegionServerRequest {
- repeated ServerName server_name = 1;
+  required ServerName server_name = 1;
+  repeated RegionSpecifier region = 2;
 }
 
-message RemoveDrainFromRegionServersResponse {
+message RecommissionRegionServerResponse {
 }
 
 message ListDeadServersRequest {
@@ -967,17 +969,17 @@ service MasterService {
   rpc ListReplicationPeers(ListReplicationPeersRequest)
     returns(ListReplicationPeersResponse);
 
-  /** Returns a list of ServerNames marked as draining. */
+  /** Returns a list of ServerNames marked as decommissioned. */
-  rpc listDrainingRegionServers(ListDrainingRegionServersRequest)
+  rpc ListDecommissionedRegionServers(ListDecommissionedRegionServersRequest)
-    returns(ListDrainingRegionServersResponse);
+    returns(ListDecommissionedRegionServersResponse);
 
-  /** Mark a list of ServerNames as draining. */
+  /** Decommission region servers. */
-  rpc drainRegionServers(DrainRegionServersRequest)
+  rpc DecommissionRegionServers(DecommissionRegionServersRequest)
-    returns(DrainRegionServersResponse);
+    returns(DecommissionRegionServersResponse);
 
-  /** Unmark a list of ServerNames marked as draining. */
+  /** Re-commission region server. */
-  rpc removeDrainFromRegionServers(RemoveDrainFromRegionServersRequest)
+  rpc RecommissionRegionServer(RecommissionRegionServerRequest)
-    returns(RemoveDrainFromRegionServersResponse);
+    returns(RecommissionRegionServerResponse);
 
   /** Fetches the Master's view of space utilization */
   rpc GetSpaceQuotaRegionSizes(GetSpaceQuotaRegionSizesRequest)

hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/MasterObserver.java

@@ -1461,4 +1461,40 @@ public interface MasterObserver {
    */
   default void postClearDeadServers(ObserverContext<MasterCoprocessorEnvironment> ctx)
       throws IOException {}
+
+  /**
+   * Called before decommission region servers.
+   */
+  default void preDecommissionRegionServers(ObserverContext<MasterCoprocessorEnvironment> ctx,
+      List<ServerName> servers, boolean offload) throws IOException {}
+
+  /**
+   * Called after decommission region servers.
+   */
+  default void postDecommissionRegionServers(ObserverContext<MasterCoprocessorEnvironment> ctx,
+      List<ServerName> servers, boolean offload) throws IOException {}
+
+  /**
+   * Called before list decommissioned region servers.
+   */
+  default void preListDecommissionedRegionServers(ObserverContext<MasterCoprocessorEnvironment> ctx)
+      throws IOException {}
+
+  /**
+   * Called after list decommissioned region servers.
+   */
+  default void postListDecommissionedRegionServers(ObserverContext<MasterCoprocessorEnvironment> ctx)
+      throws IOException {}
+
+  /**
+   * Called before recommission region server.
+   */
+  default void preRecommissionRegionServer(ObserverContext<MasterCoprocessorEnvironment> ctx,
+      ServerName server, List<byte[]> encodedRegionNames) throws IOException {}
+
+  /**
+   * Called after recommission region server.
+   */
+  default void postRecommissionRegionServer(ObserverContext<MasterCoprocessorEnvironment> ctx,
+      ServerName server, List<byte[]> encodedRegionNames) throws IOException {}
 }

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

@@ -98,6 +98,7 @@ import org.apache.hadoop.hbase.master.assignment.AssignmentManager;
 import org.apache.hadoop.hbase.master.assignment.MergeTableRegionsProcedure;
 import org.apache.hadoop.hbase.master.assignment.RegionStates;
 import org.apache.hadoop.hbase.master.assignment.RegionStates.RegionStateNode;
+import org.apache.hadoop.hbase.master.assignment.RegionStates.ServerStateNode;
 import org.apache.hadoop.hbase.master.balancer.BalancerChore;
 import org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer;
 import org.apache.hadoop.hbase.master.balancer.ClusterStatusChore;
@@ -3435,53 +3436,97 @@ public class HMaster extends HRegionServer implements MasterServices {
     return peers;
   }
 
-  @Override
+  /**
-  public void drainRegionServer(final ServerName server) {
+   * Mark region server(s) as decommissioned (previously called 'draining') to prevent additional
+   * regions from getting assigned to them. Also unload the regions on the servers asynchronously.0
+   * @param servers Region servers to decommission.
+   * @throws HBaseIOException
+   */
+  public void decommissionRegionServers(final List<ServerName> servers, final boolean offload)
+      throws HBaseIOException {
+    List<ServerName> serversAdded = new ArrayList<>(servers.size());
+    // Place the decommission marker first.
     String parentZnode = getZooKeeper().znodePaths.drainingZNode;
-    try {
+    for (ServerName server : servers) {
-      String node = ZKUtil.joinZNode(parentZnode, server.getServerName());
-      ZKUtil.createAndFailSilent(getZooKeeper(), node);
-    } catch (KeeperException ke) {
-      LOG.warn(this.zooKeeper.prefix("Unable to add drain for '" + server.getServerName() + "'."),
-        ke);
-    }
-  }
-
-  @Override
-  public List<ServerName> listDrainingRegionServers() {
-    String parentZnode = getZooKeeper().znodePaths.drainingZNode;
-    List<ServerName> serverNames = new ArrayList<>();
-    List<String> serverStrs = null;
-    try {
-      serverStrs = ZKUtil.listChildrenNoWatch(getZooKeeper(), parentZnode);
-    } catch (KeeperException ke) {
-      LOG.warn(this.zooKeeper.prefix("Unable to list draining servers."), ke);
-    }
-    // No nodes is empty draining list or ZK connectivity issues.
-    if (serverStrs == null) {
-      return serverNames;
-    }
-
-    // Skip invalid ServerNames in result
-    for (String serverStr : serverStrs) {
       try {
-        serverNames.add(ServerName.parseServerName(serverStr));
+        String node = ZKUtil.joinZNode(parentZnode, server.getServerName());
-      } catch (IllegalArgumentException iae) {
+        ZKUtil.createAndFailSilent(getZooKeeper(), node);
-        LOG.warn("Unable to cast '" + serverStr + "' to ServerName.", iae);
+      } catch (KeeperException ke) {
+        throw new HBaseIOException(
+            this.zooKeeper.prefix("Unable to decommission '" + server.getServerName() + "'."), ke);
+      }
+      if (this.serverManager.addServerToDrainList(server)) {
+        serversAdded.add(server);
+      };
+    }
+    // Move the regions off the decommissioned servers.
+    if (offload) {
+      final List<ServerName> destServers = this.serverManager.createDestinationServersList();
+      for (ServerName server : serversAdded) {
+        final List<RegionInfo> regionsOnServer =
+            this.assignmentManager.getRegionStates().getServerRegionInfoSet(server);
+        for (RegionInfo hri : regionsOnServer) {
+          ServerName dest = balancer.randomAssignment(hri, destServers);
+          if (dest == null) {
+            throw new HBaseIOException("Unable to determine a plan to move " + hri);
+          }
+          RegionPlan rp = new RegionPlan(hri, server, dest);
+          this.assignmentManager.moveAsync(rp);
+        }
       }
     }
-    return serverNames;
   }
 
-  @Override
+  /**
-  public void removeDrainFromRegionServer(ServerName server) {
+   * List region servers marked as decommissioned (previously called 'draining') to not get regions
+   * assigned to them.
+   * @return List of decommissioned servers.
+   */
+  public List<ServerName> listDecommissionedRegionServers() {
+    return this.serverManager.getDrainingServersList();
+  }
+
+  /**
+   * Remove decommission marker (previously called 'draining') from a region server to allow regions
+   * assignments. Load regions onto the server asynchronously if a list of regions is given
+   * @param server Region server to remove decommission marker from.
+   * @throws HBaseIOException
+   */
+  public void recommissionRegionServer(final ServerName server,
+      final List<byte[]> encodedRegionNames) throws HBaseIOException {
+    // Remove the server from decommissioned (draining) server list.
     String parentZnode = getZooKeeper().znodePaths.drainingZNode;
     String node = ZKUtil.joinZNode(parentZnode, server.getServerName());
     try {
       ZKUtil.deleteNodeFailSilent(getZooKeeper(), node);
     } catch (KeeperException ke) {
-      LOG.warn(
+      throw new HBaseIOException(
-        this.zooKeeper.prefix("Unable to remove drain for '" + server.getServerName() + "'."), ke);
+          this.zooKeeper.prefix("Unable to recommission '" + server.getServerName() + "'."), ke);
+    }
+    this.serverManager.removeServerFromDrainList(server);
+
+    // Load the regions onto the server if we are given a list of regions.
+    if (encodedRegionNames == null || encodedRegionNames.isEmpty()) {
+      return;
+    }
+    if (!this.serverManager.isServerOnline(server)) {
+      return;
+    }
+    for (byte[] encodedRegionName : encodedRegionNames) {
+      RegionState regionState =
+          assignmentManager.getRegionStates().getRegionState(Bytes.toString(encodedRegionName));
+      if (regionState == null) {
+        LOG.warn("Unknown region " + Bytes.toStringBinary(encodedRegionName));
+        continue;
+      }
+      RegionInfo hri = regionState.getRegion();
+      if (server.equals(regionState.getServerName())) {
+        LOG.info("Skipping move of region " + hri.getRegionNameAsString()
+          + " because region already assigned to the same server " + server + ".");
+        continue;
+      }
+      RegionPlan rp = new RegionPlan(hri, regionState.getServerName(), server);
+      this.assignmentManager.moveAsync(rp);
     }
   }
 

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

@@ -1684,4 +1684,60 @@ public class MasterCoprocessorHost
       }
     });
   }
+
+  public void preDecommissionRegionServers(List<ServerName> servers, boolean offload) throws IOException {
+    execOperation(coprocEnvironments.isEmpty() ? null : new MasterObserverOperation() {
+      @Override
+      public void call(MasterObserver observer) throws IOException {
+        observer.preDecommissionRegionServers(this, servers, offload);
+      }
+    });
+  }
+
+  public void postDecommissionRegionServers(List<ServerName> servers, boolean offload) throws IOException {
+    execOperation(coprocEnvironments.isEmpty() ? null : new MasterObserverOperation() {
+      @Override
+      public void call(MasterObserver observer) throws IOException {
+        observer.postDecommissionRegionServers(this, servers, offload);
+      }
+    });
+  }
+
+  public void preListDecommissionedRegionServers() throws IOException {
+    execOperation(coprocEnvironments.isEmpty() ? null : new MasterObserverOperation() {
+      @Override
+      public void call(MasterObserver observer) throws IOException {
+        observer.preListDecommissionedRegionServers(this);
+      }
+    });
+  }
+
+  public void postListDecommissionedRegionServers() throws IOException {
+    execOperation(coprocEnvironments.isEmpty() ? null : new MasterObserverOperation() {
+      @Override
+      public void call(MasterObserver observer) throws IOException {
+        observer.postListDecommissionedRegionServers(this);
+      }
+    });
+  }
+
+  public void preRecommissionRegionServer(ServerName server, List<byte[]> encodedRegionNames)
+      throws IOException {
+    execOperation(coprocEnvironments.isEmpty() ? null : new MasterObserverOperation() {
+      @Override
+      public void call(MasterObserver observer) throws IOException {
+        observer.preRecommissionRegionServer(this, server, encodedRegionNames);
+      }
+    });
+  }
+
+  public void postRecommissionRegionServer(ServerName server, List<byte[]> encodedRegionNames)
+      throws IOException {
+    execOperation(coprocEnvironments.isEmpty() ? null : new MasterObserverOperation() {
+      @Override
+      public void call(MasterObserver observer) throws IOException {
+        observer.postRecommissionRegionServer(this, server, encodedRegionNames);
+      }
+    });
+  }
 }

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

@@ -27,6 +27,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -119,6 +120,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateName
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateNamespaceResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateTableRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.CreateTableResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DecommissionRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DecommissionRegionServersResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteColumnRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteColumnResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteNamespaceRequest;
@@ -129,8 +132,6 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteTabl
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DeleteTableResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DisableTableRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DisableTableResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DrainRegionServersRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.DrainRegionServersResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.EnableCatalogJanitorRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.EnableCatalogJanitorResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.EnableTableRequest;
@@ -177,8 +178,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsSplitOrM
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.IsSplitOrMergeEnabledResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDeadServersRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDeadServersResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDrainingRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDecommissionedRegionServersRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDrainingRegionServersResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListDecommissionedRegionServersResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListNamespaceDescriptorsRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListNamespaceDescriptorsResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ListTableDescriptorsByNamespaceRequest;
@@ -203,8 +204,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.NormalizeR
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.NormalizeResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.OfflineRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.OfflineRegionResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RemoveDrainFromRegionServersRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RecommissionRegionServerRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RemoveDrainFromRegionServersResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RecommissionRegionServerResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RestoreSnapshotRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RestoreSnapshotResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RunCatalogScanRequest;
@@ -1902,15 +1903,21 @@ public class MasterRpcServices extends RSRpcServices
   }
 
   @Override
-  public ListDrainingRegionServersResponse listDrainingRegionServers(RpcController controller,
+  public ListDecommissionedRegionServersResponse listDecommissionedRegionServers(
-      ListDrainingRegionServersRequest request) throws ServiceException {
+      RpcController controller, ListDecommissionedRegionServersRequest request)
-    ListDrainingRegionServersResponse.Builder response =
+      throws ServiceException {
-        ListDrainingRegionServersResponse.newBuilder();
+    ListDecommissionedRegionServersResponse.Builder response =
+        ListDecommissionedRegionServersResponse.newBuilder();
     try {
       master.checkInitialized();
-      List<ServerName> servers = master.listDrainingRegionServers();
+      if (master.cpHost != null) {
-      for (ServerName server : servers) {
+        master.cpHost.preListDecommissionedRegionServers();
-        response.addServerName(ProtobufUtil.toServerName(server));
+      }
+      List<ServerName> servers = master.listDecommissionedRegionServers();
+      response.addAllServerName((servers.stream().map(server -> ProtobufUtil.toServerName(server)))
+          .collect(Collectors.toList()));
+      if (master.cpHost != null) {
+        master.cpHost.postListDecommissionedRegionServers();
       }
     } catch (IOException io) {
       throw new ServiceException(io);
@@ -1920,36 +1927,48 @@ public class MasterRpcServices extends RSRpcServices
   }
 
   @Override
-  public DrainRegionServersResponse drainRegionServers(RpcController controller,
+  public DecommissionRegionServersResponse decommissionRegionServers(RpcController controller,
-      DrainRegionServersRequest request) throws ServiceException {
+      DecommissionRegionServersRequest request) throws ServiceException {
-    DrainRegionServersResponse.Builder response = DrainRegionServersResponse.newBuilder();
     try {
       master.checkInitialized();
-      for (HBaseProtos.ServerName pbServer : request.getServerNameList()) {
+      List<ServerName> servers = request.getServerNameList().stream()
-        master.drainRegionServer(ProtobufUtil.toServerName(pbServer));
+          .map(pbServer -> ProtobufUtil.toServerName(pbServer)).collect(Collectors.toList());
+      boolean offload = request.getOffload();
+      if (master.cpHost != null) {
+        master.cpHost.preDecommissionRegionServers(servers, offload);
+      }
+      master.decommissionRegionServers(servers, offload);
+      if (master.cpHost != null) {
+        master.cpHost.postDecommissionRegionServers(servers, offload);
       }
     } catch (IOException io) {
       throw new ServiceException(io);
     }
 
-    return response.build();
+    return DecommissionRegionServersResponse.newBuilder().build();
   }
 
   @Override
-  public RemoveDrainFromRegionServersResponse removeDrainFromRegionServers(RpcController controller,
+  public RecommissionRegionServerResponse recommissionRegionServer(RpcController controller,
-      RemoveDrainFromRegionServersRequest request) throws ServiceException {
+      RecommissionRegionServerRequest request) throws ServiceException {
-    RemoveDrainFromRegionServersResponse.Builder response =
-        RemoveDrainFromRegionServersResponse.newBuilder();
     try {
       master.checkInitialized();
-      for (HBaseProtos.ServerName pbServer : request.getServerNameList()) {
+      ServerName server = ProtobufUtil.toServerName(request.getServerName());
-        master.removeDrainFromRegionServer(ProtobufUtil.toServerName(pbServer));
+      List<byte[]> encodedRegionNames = request.getRegionList().stream()
+          .map(regionSpecifier -> regionSpecifier.getValue().toByteArray())
+          .collect(Collectors.toList());
+      if (master.cpHost != null) {
+        master.cpHost.preRecommissionRegionServer(server, encodedRegionNames);
+      }
+      master.recommissionRegionServer(server, encodedRegionNames);
+      if (master.cpHost != null) {
+        master.cpHost.postRecommissionRegionServer(server, encodedRegionNames);
       }
     } catch (IOException io) {
       throw new ServiceException(io);
     }
 
-    return response.build();
+    return RecommissionRegionServerResponse.newBuilder().build();
   }
 
   @Override

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

@@ -21,6 +21,7 @@ package org.apache.hadoop.hbase.master;
 import java.io.IOException;
 import java.util.List;
 
+import org.apache.hadoop.hbase.HBaseIOException;
 import org.apache.hadoop.hbase.Server;
 import org.apache.hadoop.hbase.ServerName;
 import org.apache.hadoop.hbase.TableDescriptors;
@@ -475,24 +476,6 @@ public interface MasterServices extends Server {
   List<ReplicationPeerDescription> listReplicationPeers(String regex) throws ReplicationException,
       IOException;
 
-  /**
-   * Mark a region server as draining to prevent additional regions from getting assigned to it.
-   * @param server Region servers to drain.
-   */
-  void drainRegionServer(final ServerName server);
-
-  /**
-   * List region servers marked as draining to not get additional regions assigned to them.
-   * @return List of draining servers.
-   */
-  List<ServerName> listDrainingRegionServers();
-
-  /**
-   * Remove drain from a region server to allow additional regions assignments.
-   * @param server Region server to remove drain from.
-   */
-  void removeDrainFromRegionServer(final ServerName server);
-
   /**
    * @return {@link LockManager} to lock namespaces/tables/regions.
    */

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

@@ -42,6 +42,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.ClockOutOfSyncException;
+import org.apache.hadoop.hbase.HBaseIOException;
 import org.apache.hadoop.hbase.HConstants;
 import org.apache.hadoop.hbase.NotServingRegionException;
 import org.apache.hadoop.hbase.RegionLoad;
@@ -92,6 +93,9 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.RegionServerStatusProto
  * A server is fully processed only after the handler is fully enabled
  * and has completed the handling.
  */
+/**
+ *
+ */
 @InterfaceAudience.Private
 public class ServerManager {
   public static final String WAIT_ON_REGIONSERVERS_MAXTOSTART =
@@ -664,7 +668,7 @@ public class ServerManager {
   /*
    * Remove the server from the drain list.
    */
-  public boolean removeServerFromDrainList(final ServerName sn) {
+  public synchronized boolean removeServerFromDrainList(final ServerName sn) {
     // Warn if the server (sn) is not online.  ServerName is of the form:
     // <hostname> , <port> , <startcode>
 
@@ -676,10 +680,12 @@ public class ServerManager {
     return this.drainingServers.remove(sn);
   }
 
-  /*
+  /**
    * Add the server to the drain list.
+   * @param sn
+   * @return True if the server is added or the server is already on the drain list.
    */
-  public boolean addServerToDrainList(final ServerName sn) {
+  public synchronized boolean addServerToDrainList(final ServerName sn) {
     // Warn if the server (sn) is not online.  ServerName is of the form:
     // <hostname> , <port> , <startcode>
 
@@ -693,7 +699,7 @@ public class ServerManager {
     if (this.drainingServers.contains(sn)) {
       LOG.warn("Server " + sn + " is already in the draining server list." +
                "Ignoring request to add it again.");
-      return false;
+      return true;
     }
     LOG.info("Server " + sn + " added to draining server list.");
     return this.drainingServers.add(sn);

hbase-server/src/main/java/org/apache/hadoop/hbase/security/access/AccessController.java

@@ -1504,6 +1504,23 @@ public class AccessController implements MasterCoprocessor, RegionCoprocessor,
     requirePermission(getActiveUser(ctx), "clearDeadServers", Action.ADMIN);
   }
 
+  @Override
+  public void preDecommissionRegionServers(ObserverContext<MasterCoprocessorEnvironment> ctx,
+      List<ServerName> servers, boolean offload) throws IOException {
+    requirePermission(getActiveUser(ctx), "decommissionRegionServers", Action.ADMIN);
+  }
+
+  @Override
+  public void preListDecommissionedRegionServers(ObserverContext<MasterCoprocessorEnvironment> ctx) throws IOException {
+    requirePermission(getActiveUser(ctx), "listDecommissionedRegionServers", Action.ADMIN);
+  }
+
+  @Override
+  public void preRecommissionRegionServer(ObserverContext<MasterCoprocessorEnvironment> ctx,
+      ServerName server, List<byte[]> encodedRegionNames) throws IOException {
+    requirePermission(getActiveUser(ctx), "recommissionRegionServers", Action.ADMIN);
+  }
+
   /* ---- RegionObserver implementation ---- */
 
   @Override

hbase-server/src/main/java/org/apache/hadoop/hbase/zookeeper/DrainingServerTracker.java

@@ -44,6 +44,9 @@ import org.apache.zookeeper.KeeperException;
  * <p>If an RS gets added to the draining list, we add a watcher to it and call
  * {@link ServerManager#addServerToDrainList(ServerName)}
  *
+ * <p>This class is deprecated in 2.0 because decommission/draining API goes through
+ * master in 2.0. Can remove this class in 3.0.
+ *
  */
 @InterfaceAudience.Private
 public class DrainingServerTracker extends ZooKeeperListener {

hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestAdmin2.java

@@ -27,6 +27,7 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.EnumSet;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Random;
 import java.util.concurrent.ExecutorService;
@@ -34,6 +35,7 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Collectors;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -695,65 +697,62 @@ public class TestAdmin2 {
     assertTrue(lockList.startsWith("["));
   }
 
-  /*
+  @Test(timeout = 30000)
-   * This test drains all regions so cannot be run in parallel with other tests.
+  public void testDecommissionRegionServers() throws Exception {
-   */
+    List<ServerName> decommissionedRegionServers = admin.listDecommissionedRegionServers();
-  @Ignore @Test(timeout = 30000)
+    assertTrue(decommissionedRegionServers.isEmpty());
-  public void testDrainRegionServers() throws Exception {
-    List<ServerName> drainingServers = admin.listDrainingRegionServers();
-    assertTrue(drainingServers.isEmpty());
 
-    // Drain all region servers.
+    final TableName tableName = TableName.valueOf(name.getMethodName());
-    Collection<ServerName> clusterServers =
+    TEST_UTIL.createMultiRegionTable(tableName, "f".getBytes(), 6);
-        admin.getClusterStatus(EnumSet.of(Option.LIVE_SERVERS)).getServers();
-    drainingServers = new ArrayList<>();
-    for (ServerName server : clusterServers) {
-      drainingServers.add(server);
-    }
-    admin.drainRegionServers(drainingServers);
 
-    // Check that drain lists all region servers.
+    ArrayList<ServerName> clusterRegionServers =
-    drainingServers = admin.listDrainingRegionServers();
+        new ArrayList<>(admin.getClusterStatus(EnumSet.of(Option.LIVE_SERVERS)).getServers());
-    assertEquals(clusterServers.size(), drainingServers.size());
-    for (ServerName server : clusterServers) {
-      assertTrue(drainingServers.contains(server));
-    }
 
-    // Try for 20 seconds to create table (new region). Will not complete because all RSs draining.
+    assertEquals(clusterRegionServers.size(), 3);
-    final TableName hTable = TableName.valueOf(name.getMethodName());
-    final HTableDescriptor htd = new HTableDescriptor(hTable);
-    htd.addFamily(new HColumnDescriptor("cf"));
 
-    final Runnable createTable = new Thread() {
+    HashMap<ServerName, List<RegionInfo>> serversToDecommssion = new HashMap<>();
-      @Override
+    // Get a server that has regions. We will decommission two of the servers,
-      public void run() {
+    // leaving one online.
-        try {
+    int i;
-          admin.createTable(htd);
+    for (i = 0; i < clusterRegionServers.size(); i++) {
-        } catch (IOException ioe) {
+      List<RegionInfo> regionsOnServer = admin.getRegions(clusterRegionServers.get(i));
-          assertTrue(false); // Should not get IOException.
+      if (regionsOnServer.size() > 0) {
-        }
+        serversToDecommssion.put(clusterRegionServers.get(i), regionsOnServer);
+        break;
       }
-    };
-
-    final ExecutorService executor = Executors.newSingleThreadExecutor();
-    final java.util.concurrent.Future<?> future = executor.submit(createTable);
-    executor.shutdown();
-    try {
-      future.get(20, TimeUnit.SECONDS);
-    } catch (TimeoutException ie) {
-      assertTrue(true); // Expecting timeout to happen.
     }
 
-    // Kill executor if still processing.
+    clusterRegionServers.remove(i);
-    if (!executor.isTerminated()) {
+    // Get another server to decommission.
-      executor.shutdownNow();
+    serversToDecommssion.put(clusterRegionServers.get(0),
-      assertTrue(true);
+      admin.getRegions(clusterRegionServers.get(0)));
+
+    ServerName remainingServer = clusterRegionServers.get(1);
+
+    // Decommission
+    admin.decommissionRegionServers(new ArrayList<ServerName>(serversToDecommssion.keySet()), true);
+    assertEquals(2, admin.listDecommissionedRegionServers().size());
+
+    // Verify the regions have been off the decommissioned servers, all on the one
+    // remaining server.
+    for (ServerName server : serversToDecommssion.keySet()) {
+      for (RegionInfo region : serversToDecommssion.get(server)) {
+        TEST_UTIL.assertRegionOnServer(region, remainingServer, 10000);
+      }
     }
 
-    // Remove drain list.
+    // Recommission and load the regions.
-    admin.removeDrainFromRegionServers(drainingServers);
+    for (ServerName server : serversToDecommssion.keySet()) {
-    drainingServers = admin.listDrainingRegionServers();
+      List<byte[]> encodedRegionNames = serversToDecommssion.get(server).stream()
-    assertTrue(drainingServers.isEmpty());
+          .map(region -> region.getEncodedNameAsBytes()).collect(Collectors.toList());
-
+      admin.recommissionRegionServer(server, encodedRegionNames);
+    }
+    assertTrue(admin.listDecommissionedRegionServers().isEmpty());
+    // Verify the regions have been moved to the recommissioned servers
+    for (ServerName server : serversToDecommssion.keySet()) {
+      for (RegionInfo region : serversToDecommssion.get(server)) {
+        TEST_UTIL.assertRegionOnServer(region, server, 10000);
+      }
+    }
   }
 }

hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestAsyncDecommissionAdminApi.java

@@ -0,0 +1,95 @@
+/**
+ * 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 static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.util.ArrayList;
+import java.util.EnumSet;
+import java.util.HashMap;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.apache.hadoop.hbase.ServerName;
+import org.apache.hadoop.hbase.ClusterStatus.Option;
+import org.apache.hadoop.hbase.testclassification.ClientTests;
+import org.apache.hadoop.hbase.testclassification.MediumTests;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+@RunWith(Parameterized.class)
+@Category({ ClientTests.class, MediumTests.class })
+public class TestAsyncDecommissionAdminApi extends TestAsyncAdminBase {
+
+  @Test(timeout = 30000)
+  public void testAsyncDecommissionRegionServers() throws Exception {
+    List<ServerName> decommissionedRegionServers = admin.listDecommissionedRegionServers().get();
+    assertTrue(decommissionedRegionServers.isEmpty());
+
+    TEST_UTIL.createMultiRegionTable(tableName, FAMILY, 4);
+
+    ArrayList<ServerName> clusterRegionServers =
+        new ArrayList<>(admin.getClusterStatus(EnumSet.of(Option.LIVE_SERVERS)).get().getServers());
+
+    assertEquals(clusterRegionServers.size(), 2);
+
+    HashMap<ServerName, List<RegionInfo>> serversToDecommssion = new HashMap<>();
+    // Get a server that has regions. We will decommission one of the servers,
+    // leaving one online.
+    int i;
+    for (i = 0; i < clusterRegionServers.size(); i++) {
+      List<RegionInfo> regionsOnServer = admin.getOnlineRegions(clusterRegionServers.get(i)).get();
+      if (regionsOnServer.size() > 0) {
+        serversToDecommssion.put(clusterRegionServers.get(i), regionsOnServer);
+        break;
+      }
+    }
+
+    clusterRegionServers.remove(i);
+    ServerName remainingServer = clusterRegionServers.get(0);
+
+    // Decommission
+    admin.decommissionRegionServers(new ArrayList<ServerName>(serversToDecommssion.keySet()),
+        true).get();
+    assertEquals(1, admin.listDecommissionedRegionServers().get().size());
+
+    // Verify the regions have been off the decommissioned servers, all on the remaining server.
+    for (ServerName server : serversToDecommssion.keySet()) {
+      for (RegionInfo region : serversToDecommssion.get(server)) {
+        TEST_UTIL.assertRegionOnServer(region, remainingServer, 10000);
+      }
+    }
+
+    // Recommission and load regions
+    for (ServerName server : serversToDecommssion.keySet()) {
+      List<byte[]> encodedRegionNames = serversToDecommssion.get(server).stream()
+          .map(region -> region.getEncodedNameAsBytes()).collect(Collectors.toList());
+      admin.recommissionRegionServer(server, encodedRegionNames).get();
+    }
+    assertTrue(admin.listDecommissionedRegionServers().get().isEmpty());
+    // Verify the regions have been moved to the recommissioned servers
+    for (ServerName server : serversToDecommssion.keySet()) {
+      for (RegionInfo region : serversToDecommssion.get(server)) {
+        TEST_UTIL.assertRegionOnServer(region, server, 10000);
+      }
+    }
+  }
+}

hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestAsyncDrainAdminApi.java

@@ -1,101 +0,0 @@
-/**
- * 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 static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.List;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.TimeoutException;
-
-import org.apache.hadoop.hbase.ServerName;
-import org.apache.hadoop.hbase.testclassification.ClientTests;
-import org.apache.hadoop.hbase.testclassification.MediumTests;
-import org.junit.Ignore;
-import org.junit.Test;
-import org.junit.experimental.categories.Category;
-import org.junit.runner.RunWith;
-import org.junit.runners.Parameterized;
-
-@RunWith(Parameterized.class)
-@Category({ ClientTests.class, MediumTests.class })
-public class TestAsyncDrainAdminApi extends TestAsyncAdminBase {
-
-  /*
-   * This test drains all regions so cannot be run in parallel with other tests.
-   */
-  @Ignore @Test(timeout = 30000)
-  public void testDrainRegionServers() throws Exception {
-    List<ServerName> drainingServers = admin.listDrainingRegionServers().get();
-    assertTrue(drainingServers.isEmpty());
-
-    // Drain all region servers.
-    Collection<ServerName> clusterServers = admin.getRegionServers().get();
-    drainingServers = new ArrayList<>();
-    for (ServerName server : clusterServers) {
-      drainingServers.add(server);
-    }
-    admin.drainRegionServers(drainingServers).join();
-
-    // Check that drain lists all region servers.
-    drainingServers = admin.listDrainingRegionServers().get();
-    assertEquals(clusterServers.size(), drainingServers.size());
-    for (ServerName server : clusterServers) {
-      assertTrue(drainingServers.contains(server));
-    }
-
-    // Try for 20 seconds to create table (new region). Will not complete because all RSs draining.
-    TableDescriptorBuilder builder = TableDescriptorBuilder.newBuilder(tableName);
-    builder.addColumnFamily(ColumnFamilyDescriptorBuilder.of(FAMILY));
-    final Runnable createTable = new Thread() {
-      @Override
-      public void run() {
-        try {
-          admin.createTable(builder.build()).join();
-        } catch (Exception ioe) {
-          assertTrue(false); // Should not get IOException.
-        }
-      }
-    };
-
-    final ExecutorService executor = Executors.newSingleThreadExecutor();
-    final java.util.concurrent.Future<?> future = executor.submit(createTable);
-    executor.shutdown();
-    try {
-      future.get(20, TimeUnit.SECONDS);
-    } catch (TimeoutException ie) {
-      assertTrue(true); // Expecting timeout to happen.
-    }
-
-    // Kill executor if still processing.
-    if (!executor.isTerminated()) {
-      executor.shutdownNow();
-      assertTrue(true);
-    }
-
-    // Remove drain list.
-    admin.removeDrainFromRegionServers(drainingServers);
-    drainingServers = admin.listDrainingRegionServers().get();
-    assertTrue(drainingServers.isEmpty());
-  }
-}

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

@@ -408,21 +408,6 @@ public class MockNoopMasterServices implements MasterServices, Server {
   public void disableReplicationPeer(String peerId) throws ReplicationException, IOException {
   }
 
-  @Override
-  public void drainRegionServer(ServerName server) {
-    return;
-  }
-
-  @Override
-  public List<ServerName> listDrainingRegionServers() {
-    return null;
-  }
-
-  @Override
-  public void removeDrainFromRegionServer(ServerName servers) {
-    return;
-  }
-
   @Override
   public ReplicationPeerConfig getReplicationPeerConfig(String peerId) throws ReplicationException,
       IOException {

hbase-server/src/test/java/org/apache/hadoop/hbase/zookeeper/TestZooKeeperACL.java

@@ -325,19 +325,19 @@ public class TestZooKeeperACL {
     if (!secureZKAvailable) {
       return;
     }
-    List<ServerName> drainingServers = new ArrayList<>(1);
+    List<ServerName> decommissionedServers = new ArrayList<>(1);
-    drainingServers.add(ServerName.parseServerName("ZZZ,123,123"));
+    decommissionedServers.add(ServerName.parseServerName("ZZZ,123,123"));
 
     // If unable to connect to secure ZK cluster then this operation would fail.
-    TEST_UTIL.getAdmin().drainRegionServers(drainingServers);
+    TEST_UTIL.getAdmin().decommissionRegionServers(decommissionedServers, false);
 
-    drainingServers = TEST_UTIL.getAdmin().listDrainingRegionServers();
+    decommissionedServers = TEST_UTIL.getAdmin().listDecommissionedRegionServers();
-    assertEquals(1, drainingServers.size());
+    assertEquals(1, decommissionedServers.size());
-    assertEquals(ServerName.parseServerName("ZZZ,123,123"), drainingServers.get(0));
+    assertEquals(ServerName.parseServerName("ZZZ,123,123"), decommissionedServers.get(0));
 
-    TEST_UTIL.getAdmin().removeDrainFromRegionServers(drainingServers);
+    TEST_UTIL.getAdmin().recommissionRegionServer(decommissionedServers.get(0), null);
-    drainingServers = TEST_UTIL.getAdmin().listDrainingRegionServers();
+    decommissionedServers = TEST_UTIL.getAdmin().listDecommissionedRegionServers();
-    assertEquals(0, drainingServers.size());
+    assertEquals(0, decommissionedServers.size());
   }
 
 }