HBASE-27551 Add config options to delay assignment to retain last region location

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

@@ -406,7 +406,7 @@ private void checkIsDead(final ServerName serverName, final String what)
    * Assumes onlineServers is locked.
    * @return ServerName with matching hostname and port.
    */
-  private ServerName findServerWithSameHostnamePortWithLock(final ServerName serverName) {
+  public ServerName findServerWithSameHostnamePortWithLock(final ServerName serverName) {
     ServerName end =
       ServerName.valueOf(serverName.getHostname(), serverName.getPort(), Long.MAX_VALUE);
 

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

@@ -153,6 +153,25 @@ public class AssignmentManager {
   private static final int DEFAULT_RIT_STUCK_WARNING_THRESHOLD = 60 * 1000;
   public static final String UNEXPECTED_STATE_REGION = "Unexpected state for ";
 
+  public static final String FORCE_REGION_RETAINMENT = "hbase.master.scp.retain.assignment.force";
+
+  public static final boolean DEFAULT_FORCE_REGION_RETAINMENT = false;
+
+  /** The wait time in millis before checking again if the region's previous RS is back online */
+  public static final String FORCE_REGION_RETAINMENT_WAIT =
+    "hbase.master.scp.retain.assignment.force.wait";
+
+  public static final int DEFAULT_FORCE_REGION_RETAINMENT_WAIT = 100;
+
+  /**
+   * The number of times to check if the region's previous RS is back online, before giving up and
+   * proceeding with assignment on a new RS
+   */
+  public static final String FORCE_REGION_RETAINMENT_RETRIES =
+    "hbase.master.scp.retain.assignment.force.retries";
+
+  public static final long DEFAULT_FORCE_REGION_RETAINMENT_RETRIES = 600;
+
   private final ProcedureEvent<?> metaAssignEvent = new ProcedureEvent<>("meta assign");
   private final ProcedureEvent<?> metaLoadEvent = new ProcedureEvent<>("meta load");
 
@@ -201,6 +220,12 @@ public class AssignmentManager {
 
   private Thread assignThread;
 
+  private final boolean forceRegionRetainment;
+
+  private final int forceRegionRetainmentWait;
+
+  private final long forceRegionRetainmentRetries;
+
   public AssignmentManager(MasterServices master, MasterRegion masterRegion) {
     this(master, masterRegion, new RegionStateStore(master, masterRegion));
   }
@@ -240,6 +265,13 @@ public AssignmentManager(MasterServices master, MasterRegion masterRegion) {
     }
     minVersionToMoveSysTables =
       conf.get(MIN_VERSION_MOVE_SYS_TABLES_CONFIG, DEFAULT_MIN_VERSION_MOVE_SYS_TABLES_CONFIG);
+
+    forceRegionRetainment =
+      conf.getBoolean(FORCE_REGION_RETAINMENT, DEFAULT_FORCE_REGION_RETAINMENT);
+    forceRegionRetainmentWait =
+      conf.getInt(FORCE_REGION_RETAINMENT_WAIT, DEFAULT_FORCE_REGION_RETAINMENT_WAIT);
+    forceRegionRetainmentRetries =
+      conf.getLong(FORCE_REGION_RETAINMENT_RETRIES, DEFAULT_FORCE_REGION_RETAINMENT_RETRIES);
   }
 
   private void mirrorMetaLocations() throws IOException, KeeperException {
@@ -410,6 +442,18 @@ int getAssignMaxAttempts() {
     return assignMaxAttempts;
   }
 
+  public boolean isForceRegionRetainment() {
+    return forceRegionRetainment;
+  }
+
+  public int getForceRegionRetainmentWait() {
+    return forceRegionRetainmentWait;
+  }
+
+  public long getForceRegionRetainmentRetries() {
+    return forceRegionRetainmentRetries;
+  }
+
   int getAssignRetryImmediatelyMaxAttempts() {
     return assignRetryImmediatelyMaxAttempts;
   }

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

@@ -20,6 +20,7 @@
 import static org.apache.hadoop.hbase.io.hfile.CacheConfig.DEFAULT_EVICT_ON_CLOSE;
 import static org.apache.hadoop.hbase.io.hfile.CacheConfig.EVICT_BLOCKS_ON_CLOSE_KEY;
 import static org.apache.hadoop.hbase.master.LoadBalancer.BOGUS_SERVER_NAME;
+import static org.apache.hadoop.hbase.master.assignment.AssignmentManager.FORCE_REGION_RETAINMENT;
 
 import edu.umd.cs.findbugs.annotations.Nullable;
 import java.io.IOException;
@@ -31,6 +32,7 @@
 import org.apache.hadoop.hbase.client.RetriesExhaustedException;
 import org.apache.hadoop.hbase.master.MetricsAssignmentManager;
 import org.apache.hadoop.hbase.master.RegionState.State;
+import org.apache.hadoop.hbase.master.ServerManager;
 import org.apache.hadoop.hbase.master.procedure.AbstractStateMachineRegionProcedure;
 import org.apache.hadoop.hbase.master.procedure.MasterProcedureEnv;
 import org.apache.hadoop.hbase.master.procedure.ServerCrashProcedure;
@@ -95,6 +97,10 @@
  * Notice that, although we allow specify a target server, it just acts as a candidate, we do not
  * guarantee that the region will finally be on the target server. If this is important for you, you
  * should check whether the region is on the target server after the procedure is finished.
+ * </p>
+ * Altenatively, for trying retaining assignments, the
+ * <b>hbase.master.scp.retain.assignment.force</b> option can be used together with
+ * <b>hbase.master.scp.retain.assignment</b>.
  * <p/>
  * When you want to schedule a TRSP, please check whether there is still one for this region, and
  * the check should be under the RegionStateNode lock. We will remove the TRSP from a
@@ -126,6 +132,8 @@ public class TransitRegionStateProcedure
 
   private boolean isSplit;
 
+  private long retries;
+
   public TransitRegionStateProcedure() {
   }
 
@@ -188,6 +196,27 @@ protected boolean waitInitialized(MasterProcedureEnv env) {
     return am.waitMetaLoaded(this) || am.waitMetaAssigned(this, getRegion());
   }
 
+  private void checkAndWaitForOriginalServer(MasterProcedureEnv env, ServerName lastHost)
+    throws ProcedureSuspendedException {
+    ServerManager serverManager = env.getMasterServices().getServerManager();
+    ServerName newNameForServer = serverManager.findServerWithSameHostnamePortWithLock(lastHost);
+    boolean isOnline = serverManager.createDestinationServersList().contains(newNameForServer);
+
+    if (!isOnline && retries < env.getAssignmentManager().getForceRegionRetainmentRetries()) {
+      retries++;
+      LOG.info("Suspending the TRSP PID={} because {} is true and previous host {} "
+        + "for region is not yet online.", this.getProcId(), FORCE_REGION_RETAINMENT, lastHost);
+      setTimeout(env.getAssignmentManager().getForceRegionRetainmentWait());
+      setState(ProcedureProtos.ProcedureState.WAITING_TIMEOUT);
+      throw new ProcedureSuspendedException();
+    }
+    LOG.info(
+      "{} is true. TRSP PID={} waited {}ms for host {} to come back online. "
+        + "Did host come back online? {}",
+      FORCE_REGION_RETAINMENT, this.getProcId(),
+      (retries * env.getAssignmentManager().getForceRegionRetainmentWait()), lastHost, isOnline);
+  }
+
   private void queueAssign(MasterProcedureEnv env, RegionStateNode regionNode)
     throws ProcedureSuspendedException {
     boolean retain = false;
@@ -200,9 +229,18 @@ private void queueAssign(MasterProcedureEnv env, RegionStateNode regionNode)
         regionNode.setRegionLocation(assignCandidate);
       } else if (regionNode.getLastHost() != null) {
         retain = true;
-        LOG.info("Setting lastHost as the region location {}", regionNode.getLastHost());
+        LOG.info("Setting lastHost {} as the location for region {}", regionNode.getLastHost(),
+          regionNode.getRegionInfo().getEncodedName());
         regionNode.setRegionLocation(regionNode.getLastHost());
       }
+      if (
+        regionNode.getRegionLocation() != null
+          && env.getAssignmentManager().isForceRegionRetainment()
+      ) {
+        LOG.warn("{} is set to true. This may delay regions re-assignment "
+          + "upon RegionServers crashes or restarts.", FORCE_REGION_RETAINMENT);
+        checkAndWaitForOriginalServer(env, regionNode.getRegionLocation());
+      }
     }
     LOG.info("Starting {}; {}; forceNewPlan={}, retain={}", this, regionNode.toShortString(),
       forceNewPlan, retain);

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

@@ -17,6 +17,9 @@
  */
 package org.apache.hadoop.hbase.master;
 
+import static org.apache.hadoop.hbase.master.assignment.AssignmentManager.FORCE_REGION_RETAINMENT;
+import static org.apache.hadoop.hbase.master.assignment.AssignmentManager.FORCE_REGION_RETAINMENT_WAIT;
+import static org.apache.hadoop.hbase.master.procedure.ServerCrashProcedure.MASTER_SCP_RETAIN_ASSIGNMENT;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertTrue;
@@ -33,7 +36,6 @@
 import org.apache.hadoop.hbase.StartTestingClusterOption;
 import org.apache.hadoop.hbase.TableName;
 import org.apache.hadoop.hbase.client.RegionInfo;
-import org.apache.hadoop.hbase.master.procedure.ServerCrashProcedure;
 import org.apache.hadoop.hbase.testclassification.MasterTests;
 import org.apache.hadoop.hbase.testclassification.MediumTests;
 import org.apache.hadoop.hbase.util.JVMClusterUtil;
@@ -190,6 +192,7 @@ public void testRetainAssignmentOnSingleRSRestart() throws Exception {
     cluster.stopMaster(0);
     cluster.waitForMasterToStop(master.getServerName(), 5000);
     cluster.stopRegionServer(deadRS);
+    cluster.waitForRegionServerToStop(deadRS, 5000);
 
     LOG.info("\n\nSleeping a bit");
     Thread.sleep(2000);
@@ -228,13 +231,85 @@ public void testRetainAssignmentOnSingleRSRestart() throws Exception {
     }
   }
 
+  /**
+   * This tests the force retaining assignments upon an RS restart, even when master triggers an SCP
+   */
+  @Test
+  public void testForceRetainAssignment() throws Exception {
+    UTIL.getConfiguration().setBoolean(FORCE_REGION_RETAINMENT, true);
+    UTIL.getConfiguration().setLong(FORCE_REGION_RETAINMENT_WAIT, 100);
+    setupCluster();
+    HMaster master = UTIL.getMiniHBaseCluster().getMaster();
+    SingleProcessHBaseCluster cluster = UTIL.getHBaseCluster();
+    List<JVMClusterUtil.RegionServerThread> threads = cluster.getLiveRegionServerThreads();
+    assertEquals(NUM_OF_RS, threads.size());
+    int[] rsPorts = new int[NUM_OF_RS];
+    for (int i = 0; i < NUM_OF_RS; i++) {
+      rsPorts[i] = threads.get(i).getRegionServer().getServerName().getPort();
+    }
+
+    // We don't have to use SnapshotOfRegionAssignmentFromMeta. We use it here because AM used to
+    // use it to load all user region placements
+    SnapshotOfRegionAssignmentFromMeta snapshot =
+      new SnapshotOfRegionAssignmentFromMeta(master.getConnection());
+    snapshot.initialize();
+    Map<RegionInfo, ServerName> regionToRegionServerMap = snapshot.getRegionToRegionServerMap();
+    for (ServerName serverName : regionToRegionServerMap.values()) {
+      boolean found = false; // Test only, no need to optimize
+      for (int k = 0; k < NUM_OF_RS && !found; k++) {
+        found = serverName.getPort() == rsPorts[k];
+      }
+      LOG.info("Server {} has regions? {}", serverName, found);
+      assertTrue(found);
+    }
+
+    // Server to be restarted
+    ServerName deadRS = threads.get(0).getRegionServer().getServerName();
+    LOG.info("\n\nStopping {} server", deadRS);
+    cluster.stopRegionServer(deadRS);
+
+    LOG.info("\n\nSleeping a bit");
+    Thread.sleep(2000);
+
+    LOG.info("\n\nStarting region server {} second time with the same port", deadRS);
+    cluster.getConf().setInt(ServerManager.WAIT_ON_REGIONSERVERS_MINTOSTART, 3);
+    cluster.getConf().setInt(HConstants.REGIONSERVER_PORT, deadRS.getPort());
+    cluster.startRegionServer();
+
+    ensureServersWithSamePort(master, rsPorts);
+
+    // Wait till master is initialized and all regions are assigned
+    for (TableName TABLE : TABLES) {
+      UTIL.waitTableAvailable(TABLE);
+    }
+    UTIL.waitUntilNoRegionsInTransition(60000);
+    snapshot = new SnapshotOfRegionAssignmentFromMeta(master.getConnection());
+    snapshot.initialize();
+    Map<RegionInfo, ServerName> newRegionToRegionServerMap = snapshot.getRegionToRegionServerMap();
+    assertEquals(regionToRegionServerMap.size(), newRegionToRegionServerMap.size());
+    for (Map.Entry<RegionInfo, ServerName> entry : newRegionToRegionServerMap.entrySet()) {
+      ServerName oldServer = regionToRegionServerMap.get(entry.getKey());
+      ServerName currentServer = entry.getValue();
+      LOG.info(
+        "Key=" + entry.getKey() + " oldServer=" + oldServer + ", currentServer=" + currentServer);
+      assertEquals(entry.getKey().toString(), oldServer.getAddress(), currentServer.getAddress());
+
+      if (deadRS.getPort() == oldServer.getPort()) {
+        // Restarted RS start code wont be same
+        assertNotEquals(oldServer.getStartcode(), currentServer.getStartcode());
+      } else {
+        assertEquals(oldServer.getStartcode(), currentServer.getStartcode());
+      }
+    }
+  }
+
   private void setupCluster() throws Exception, IOException, InterruptedException {
     // Set Zookeeper based connection registry since we will stop master and start a new master
     // without populating the underlying config for the connection.
     UTIL.getConfiguration().set(HConstants.CLIENT_CONNECTION_REGISTRY_IMPL_CONF_KEY,
       HConstants.ZK_CONNECTION_REGISTRY_CLASS);
     // Enable retain assignment during ServerCrashProcedure
-    UTIL.getConfiguration().setBoolean(ServerCrashProcedure.MASTER_SCP_RETAIN_ASSIGNMENT, true);
+    UTIL.getConfiguration().setBoolean(MASTER_SCP_RETAIN_ASSIGNMENT, true);
     UTIL.startMiniCluster(StartTestingClusterOption.builder().masterClass(HMasterForTest.class)
       .numRegionServers(NUM_OF_RS).build());