HDFS-3026. HA: Handle failure during HA state transition. Contributed by Aaron T. Myers.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1337031 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -532,6 +532,8 @@ Release 2.0.0 - UNRELEASED
     necessarily a BlockInfoUnderConstruction, so do not cast it in
     FSNamesystem.recoverLeaseInternal(..).  (szetszwo)
 
+    HDFS-3026. HA: Handle failure during HA state transition. (atm)
+
   BREAKDOWN OF HDFS-1623 SUBTASKS
 
     HDFS-2179. Add fencing framework and mechanisms for NameNode HA. (todd)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNode.java

@@ -206,6 +206,7 @@ public class NameNode {
   private final boolean haEnabled;
   private final HAContext haContext;
   protected boolean allowStaleStandbyReads;
+  private Runtime runtime = Runtime.getRuntime();
 
   
   /** httpServer */
@@ -481,11 +482,16 @@ public class NameNode {
   }
   
   private void startTrashEmptier(Configuration conf) throws IOException {
-    long trashInterval 
-      = conf.getLong(CommonConfigurationKeys.FS_TRASH_INTERVAL_KEY, 
+    long trashInterval = conf.getLong(
+        CommonConfigurationKeys.FS_TRASH_INTERVAL_KEY,
         CommonConfigurationKeys.FS_TRASH_INTERVAL_DEFAULT);
-    if(trashInterval == 0)
+    if (trashInterval == 0) {
       return;
+    } else if (trashInterval < 0) {
+      throw new IOException("Cannot start tresh emptier with negative interval."
+          + " Set " + CommonConfigurationKeys.FS_TRASH_INTERVAL_KEY + " to a"
+          + " positive value.");
+    }
     this.emptier = new Thread(new Trash(conf).getEmptier(), "Trash Emptier");
     this.emptier.setDaemon(true);
     this.emptier.start();
@@ -1236,13 +1242,36 @@ public class NameNode {
     return state.getServiceState();
   }
   
+  @VisibleForTesting
+  public synchronized void setRuntimeForTesting(Runtime runtime) {
+    this.runtime = runtime;
+  }
+
   /**
-   * Class used as expose {@link NameNode} as context to {@link HAState}
+   * Shutdown the NN immediately in an ungraceful way. Used when it would be
+   * unsafe for the NN to continue operating, e.g. during a failed HA state
+   * transition.
    * 
-   * TODO(HA):
-   * When entering and exiting state, on failing to start services,
-   * appropriate action is needed todo either shutdown the node or recover
-   * from failure.
+   * @param t exception which warrants the shutdown. Printed to the NN log
+   *          before exit.
+   * @throws ServiceFailedException thrown only for testing.
+   */
+  private synchronized void doImmediateShutdown(Throwable t)
+      throws ServiceFailedException {
+    String message = "Error encountered requiring NN shutdown. " +
+        "Shutting down immediately.";
+    try {
+      LOG.fatal(message, t);
+    } catch (Throwable ignored) {
+      // This is unlikely to happen, but there's nothing we can do if it does.
+    }
+    runtime.exit(1);
+    // This code is only reached during testing, when runtime is stubbed out.
+    throw new ServiceFailedException(message, t);
+  }
+  
+  /**
+   * Class used to expose {@link NameNode} as context to {@link HAState}
    */
   protected class NameNodeHAContext implements HAContext {
     @Override
@@ -1257,33 +1286,53 @@ public class NameNode {
 
     @Override
     public void startActiveServices() throws IOException {
+      try {
         namesystem.startActiveServices();
         startTrashEmptier(conf);
+      } catch (Throwable t) {
+        doImmediateShutdown(t);
+      }
     }
 
     @Override
     public void stopActiveServices() throws IOException {
+      try {
         if (namesystem != null) {
           namesystem.stopActiveServices();
         }
         stopTrashEmptier();
+      } catch (Throwable t) {
+        doImmediateShutdown(t);
+      }
     }
 
     @Override
     public void startStandbyServices() throws IOException {
+      try {
         namesystem.startStandbyServices(conf);
+      } catch (Throwable t) {
+        doImmediateShutdown(t);
+      }
     }
 
     @Override
     public void prepareToStopStandbyServices() throws ServiceFailedException {
+      try {
         namesystem.prepareToStopStandbyServices();
+      } catch (Throwable t) {
+        doImmediateShutdown(t);
+      }
     }
     
     @Override
     public void stopStandbyServices() throws IOException {
+      try {
         if (namesystem != null) {
           namesystem.stopStandbyServices();
         }
+      } catch (Throwable t) {
+        doImmediateShutdown(t);
+      }
     }
     
     @Override

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestStateTransitionFailure.java

@@ -0,0 +1,80 @@
+/**
+ * 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.hdfs.server.namenode.ha;
+
+import static org.apache.hadoop.test.GenericTestUtils.assertExceptionContains;
+import static org.junit.Assert.fail;
+import static org.mockito.Matchers.anyInt;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import java.io.IOException;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.CommonConfigurationKeys;
+import org.apache.hadoop.ha.ServiceFailedException;
+import org.apache.hadoop.hdfs.MiniDFSCluster;
+import org.apache.hadoop.hdfs.MiniDFSNNTopology;
+import org.junit.Test;
+
+/**
+ * Tests to verify the behavior of failing to fully start transition HA states.
+ */
+public class TestStateTransitionFailure {
+  
+  public static final Log LOG = LogFactory.getLog(TestStateTransitionFailure.class);
+
+  /**
+   * Ensure that a failure to fully transition to the active state causes a
+   * shutdown of the NameNode.
+   */
+  @Test
+  public void testFailureToTransitionCausesShutdown() throws IOException {
+    MiniDFSCluster cluster = null;
+    try {
+      Configuration conf = new Configuration();
+      // Set an illegal value for the trash emptier interval. This will cause
+      // the NN to fail to transition to the active state.
+      conf.setLong(CommonConfigurationKeys.FS_TRASH_INTERVAL_KEY, -1);
+      cluster = new MiniDFSCluster.Builder(conf)
+          .nnTopology(MiniDFSNNTopology.simpleHATopology())
+          .numDataNodes(0)
+          .build();
+      cluster.waitActive();
+      Runtime mockRuntime = mock(Runtime.class);
+      cluster.getNameNode(0).setRuntimeForTesting(mockRuntime);
+      verify(mockRuntime, times(0)).exit(anyInt());
+      try {
+        cluster.transitionToActive(0);
+        fail("Transitioned to active but should not have been able to.");
+      } catch (ServiceFailedException sfe) {
+        assertExceptionContains("Error encountered requiring NN shutdown. " +
+            "Shutting down immediately.", sfe);
+        LOG.info("got expected exception", sfe);
+      }
+      verify(mockRuntime, times(1)).exit(anyInt());
+    } finally {
+      if (cluster != null) {
+        cluster.shutdown();
+      }
+    }
+  }
+}