HBASE-21078 [amv2] CODE-BUG NPE in RTP doing Unassign

hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/Procedure.java

@@ -421,7 +421,10 @@ public abstract class Procedure<TEnvironment> implements Comparable<Procedure<TE
     sb.append(", state="); // pState for Procedure State as opposed to any other kind.
     toStringState(sb);
 
-    sb.append(", hasLock=").append(locked);
+    // Only print out locked if actually locked. Most of the time it is not.
+    if (this.locked) {
+      sb.append(", locked=").append(locked);
+    }
 
     if (hasException()) {
       sb.append(", exception=" + getException());

hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/ProcedureExecutor.java

@@ -1725,7 +1725,8 @@ public class ProcedureExecutor<TEnvironment> {
       // children have completed, move parent to front of the queue.
       store.update(parent);
       scheduler.addFront(parent);
-      LOG.info("Finished subprocedure(s) of " + parent + "; resume parent processing.");
+      LOG.info("Finished subprocedure pid={}, resume processing parent {}",
+          procedure.getProcId(), parent);
       return;
     }
   }

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

@@ -24,17 +24,19 @@ import java.io.IOException;
 import org.apache.hadoop.hbase.HBaseIOException;
 import org.apache.hadoop.hbase.ServerName;
 import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.client.DoNotRetryRegionException;
 import org.apache.hadoop.hbase.client.RegionInfo;
 import org.apache.hadoop.hbase.master.RegionPlan;
 import org.apache.hadoop.hbase.master.procedure.AbstractStateMachineRegionProcedure;
 import org.apache.hadoop.hbase.master.procedure.MasterProcedureEnv;
 import org.apache.hadoop.hbase.procedure2.ProcedureStateSerializer;
-import org.apache.yetus.audience.InterfaceAudience;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProcedureProtos.MoveRegionState;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProcedureProtos.MoveRegionStateData;
+import org.apache.hbase.thirdparty.com.google.common.annotations.VisibleForTesting;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * Procedure that implements a RegionPlan.
@@ -55,6 +57,11 @@ public class MoveRegionProcedure extends AbstractStateMachineRegionProcedure<Mov
     super();
   }
 
+  @VisibleForTesting
+  protected RegionPlan getPlan() {
+    return this.plan;
+  }
+
   /**
    * @param check whether we should do some checks in the constructor. We will skip the checks if we
    *          are reopening a region as this may fail the whole procedure and cause stuck. We will
@@ -91,6 +98,13 @@ public class MoveRegionProcedure extends AbstractStateMachineRegionProcedure<Mov
         }
         break;
       case MOVE_REGION_UNASSIGN:
+        try {
+          checkOnline(env, this.plan.getRegionInfo());
+        } catch (DoNotRetryRegionException dnrre) {
+          LOG.info("Skipping move, {} is not online; {}", getRegion().getEncodedName(), this,
+              dnrre);
+          return Flow.NO_MORE_STATE;
+        }
         addChildProcedure(new UnassignProcedure(plan.getRegionInfo(), plan.getSource(),
             plan.getDestination(), true));
         setNextState(MoveRegionState.MOVE_REGION_ASSIGN);

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

@@ -28,6 +28,7 @@ import org.apache.hadoop.hbase.client.RegionInfo;
 import org.apache.hadoop.hbase.exceptions.UnexpectedStateException;
 import org.apache.hadoop.hbase.favored.FavoredNodesManager;
 import org.apache.hadoop.hbase.ipc.ServerNotRunningYetException;
+import org.apache.hadoop.hbase.master.RegionState;
 import org.apache.hadoop.hbase.master.RegionState.State;
 import org.apache.hadoop.hbase.master.assignment.RegionStates.RegionStateNode;
 import org.apache.hadoop.hbase.master.procedure.MasterProcedureEnv;
@@ -116,9 +117,7 @@ public class UnassignProcedure extends RegionTransitionProcedure {
     this.destinationServer = destinationServer;
     this.force = force;
     this.removeAfterUnassigning = removeAfterUnassigning;
-
-    // we don't need REGION_TRANSITION_QUEUE, we jump directly to sending the request
-    setTransitionState(RegionTransitionState.REGION_TRANSITION_DISPATCH);
+    setTransitionState(RegionTransitionState.REGION_TRANSITION_QUEUE);
   }
 
   @Override
@@ -179,9 +178,21 @@ public class UnassignProcedure extends RegionTransitionProcedure {
 
   @Override
   protected boolean startTransition(final MasterProcedureEnv env, final RegionStateNode regionNode) {
-    // nothing to do here. we skip the step in the constructor
-    // by jumping to REGION_TRANSITION_DISPATCH
-    throw new UnsupportedOperationException();
+    // Check region is actually unassignable now we have lock on it. If not skirt to end.
+    // It could have had its status changed on us post construction... perhaps a split removed
+    // the region we are to unassign (a split and a move happening near-concurrently).
+    // Don't overcheck. A region is set to have a SPLITTING state if it is the parent and it is
+    // being split. Regions that are in this RSN state are unassignable. Regions that are SPLIT
+    // are not.
+    RegionStates regionStates = env.getAssignmentManager().getRegionStates();
+    RegionState rs = regionStates.getRegionState(regionNode.getRegionInfo());
+    // Don't try unassigning regions that are closed or split. RSN state could have been set
+    // after our creation but before we got the region lock.
+    if (rs.isClosing() || rs.isClosed() || rs.isSplit() || rs.isMerged()) {
+      LOG.info("NOT unassignable {}, skipping {}", rs, this);
+      return false;
+    }
+    return true;
   }
 
   @Override

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

@@ -3215,7 +3215,6 @@ public class HRegionServer extends HasThread implements
   }
 
    /**
-   * @param regionName
    * @return HRegion for the passed binary <code>regionName</code> or null if
    *         named region is not member of the online regions.
    */

hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/TestRegionMove2.java

@@ -0,0 +1,174 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.master.assignment;
+
+import static org.junit.Assert.assertTrue;
+
+import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.stream.Collectors;
+
+import org.apache.hadoop.hbase.HBaseClassTestRule;
+import org.apache.hadoop.hbase.HBaseIOException;
+import org.apache.hadoop.hbase.HBaseTestingUtility;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.client.Admin;
+import org.apache.hadoop.hbase.client.Put;
+import org.apache.hadoop.hbase.client.RegionInfo;
+import org.apache.hadoop.hbase.client.Table;
+import org.apache.hadoop.hbase.master.HMaster;
+import org.apache.hadoop.hbase.master.RegionPlan;
+import org.apache.hadoop.hbase.master.RegionState;
+import org.apache.hadoop.hbase.master.procedure.MasterProcedureEnv;
+import org.apache.hadoop.hbase.procedure2.ProcedureTestingUtility;
+import org.apache.hadoop.hbase.regionserver.HRegionServer;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProcedureProtos;
+import org.apache.hadoop.hbase.testclassification.LargeTests;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+import org.junit.ClassRule;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+import org.junit.rules.TestName;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Like TestRegionMove in regionserver package but in here in this package so I can get access to
+ * Procedure internals to mess with the assignment to manufacture states seen out on clusters.
+ */
+@Category({LargeTests.class})
+public class TestRegionMove2 {
+  private final static Logger LOG = LoggerFactory.getLogger(TestRegionMove2.class);
+
+  @ClassRule
+  public static final HBaseClassTestRule CLASS_RULE =
+      HBaseClassTestRule.forClass(TestRegionMove2.class);
+
+  @Rule
+  public TestName name = new TestName();
+
+  private static final HBaseTestingUtility TEST_UTIL = new HBaseTestingUtility();
+
+  @BeforeClass
+  public static void startCluster() throws Exception {
+    TEST_UTIL.startMiniCluster(2);
+  }
+
+  @AfterClass
+  public static void stopCluster() throws Exception {
+    TEST_UTIL.shutdownMiniCluster();
+  }
+
+  /**
+   * Test that we make it through to the end if parent Region is offlined between start of this
+   * Move and when we go to run the move UnassignProcedure.
+   */
+  @Test
+  public void testMoveOfRegionOfflinedPostStart() throws Exception {
+    TableName tableName = TableName.valueOf(this.name.getMethodName());
+    // Create a table with more than one region
+    byte [] cf = Bytes.toBytes("cf");
+    Table t = TEST_UTIL.createMultiRegionTable(tableName, cf, 10);
+    TEST_UTIL.waitUntilAllRegionsAssigned(tableName);
+    HRegionServer rs1 = null;
+    HRegionServer rs2 = null;
+    List<RegionInfo> regionsOnRS1ForTable = null;
+    try (Admin admin = TEST_UTIL.getAdmin()) {
+      // Write an update to each region
+      for (RegionInfo regionInfo : admin.getRegions(tableName)) {
+        byte[] startKey = regionInfo.getStartKey();
+        // StartKey of first region is "empty", which would throw an error if we try to Put that.
+        byte[] rowKey =
+            org.apache.hbase.thirdparty.com.google.common.primitives.Bytes.concat(startKey,
+                Bytes.toBytes("1"));
+        Put p = new Put(rowKey);
+        p.addColumn(cf, Bytes.toBytes("q1"), Bytes.toBytes("value"));
+        t.put(p);
+      }
+
+      // Get a Region which is on the first RS
+      rs1 = TEST_UTIL.getRSForFirstRegionInTable(tableName);
+      rs2 = TEST_UTIL.getOtherRegionServer(rs1);
+      regionsOnRS1ForTable = admin.getRegions(rs1.getServerName()).stream().
+          filter((regionInfo) -> regionInfo.getTable().equals(tableName)).
+          collect(Collectors.toList());
+    }
+    assertTrue("Expected to find at least one region for " + tableName + " on " +
+        rs1.getServerName() + ", but found none", !regionsOnRS1ForTable.isEmpty());
+    final RegionInfo regionToMove = regionsOnRS1ForTable.get(0);
+    HMaster master = TEST_UTIL.getHBaseCluster().getMaster();
+
+    // Try to move the region. HackedMoveRegionProcedure should intercede and mess up the region
+    // state setting it to SPLIT when we run the UnassignProcedure part of move region.
+    // Then when we go to do the unassignprocedure, we should notice the region-to-move is not
+    // online.... spew some log, and then fast-track to the end of the unassign. The assign under
+    // move will also notice that the parent is not-online but SPLIT and will skip it... so the
+    // move will "succeed" but we won't have moved the region!
+    RegionPlan rp = new RegionPlan(regionToMove, rs1.getServerName(), rs2.getServerName());
+    MasterProcedureEnv env = master.getMasterProcedureExecutor().getEnvironment();
+    HackedMoveRegionProcedure p = new HackedMoveRegionProcedure(env, rp);
+    master.getMasterProcedureExecutor().submitProcedure(p);
+    ProcedureTestingUtility.waitProcedure(master.getMasterProcedureExecutor(), p);
+    // Split should have been called.
+    assertTrue(p.split.get());
+    // The region should not have been moved!
+    assertTrue(rs1.getOnlineRegion(regionToMove.getRegionName()) != null);
+  }
+
+  /**
+   * Class just so we can mess around with RegionStateNode state at a particular point in the
+   * Procedure to try and mess it up.
+   */
+  public static class HackedMoveRegionProcedure extends MoveRegionProcedure {
+    /**
+     * Set to true after we hack this regions RSN to SPLIT
+     */
+    public static AtomicBoolean split = new AtomicBoolean(false);
+
+    // Required by the Procedure framework to create the procedure on replay
+    public HackedMoveRegionProcedure() {
+      super();
+    }
+
+    public HackedMoveRegionProcedure(MasterProcedureEnv env, RegionPlan plan)
+        throws HBaseIOException {
+      super(env, plan, false);
+    }
+
+    @Override
+    protected Flow executeFromState(MasterProcedureEnv env,
+        MasterProcedureProtos.MoveRegionState state) throws InterruptedException {
+      Flow flow = null;
+      switch (state) {
+        case MOVE_REGION_UNASSIGN:
+          // Just before the unassign, flip the state to SPLIT. The unassign should exit!
+          RegionStates.RegionStateNode rsn =
+              env.getAssignmentManager().getRegionStates().getOrCreateRegionStateNode(getRegion());
+          rsn.setState(RegionState.State.SPLIT);
+          LOG.info("HACKED RSN, setting it to SPLIT: {}", rsn);
+          split.set(true);
+        default:
+          flow = super.executeFromState(env, state);
+      }
+      return flow;
+    }
+  }
+}