HADOOP-9703. org.apache.hadoop.ipc.Client leaks threads on stop (Tsuyoshi OZAWA via Colin Patrick McCabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1502696 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -305,6 +305,9 @@ Release 2.2.0 - UNRELEASED
     HADOOP-9417.  Support for symlink resolution in LocalFileSystem /
     RawLocalFileSystem.  (Andrew Wang via Colin Patrick McCabe)
 
+    HADOOP-9703.  org.apache.hadoop.ipc.Client leaks threads on stop.
+    (Tsuyoshi OZAWA vi Colin Patrick McCabe)
+
   OPTIMIZATIONS
 
   BUG FIXES

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Client.java

@@ -118,17 +118,70 @@ public class Client {
   private final byte[] clientId;
   
   /**
-   * Executor on which IPC calls' parameters are sent. Deferring
-   * the sending of parameters to a separate thread isolates them
-   * from thread interruptions in the calling code.
+   * Executor on which IPC calls' parameters are sent.
+   * Deferring the sending of parameters to a separate
+   * thread isolates them from thread interruptions in the
+   * calling code.
    */
-  private static final ExecutorService SEND_PARAMS_EXECUTOR = 
-    Executors.newCachedThreadPool(
+  private final ExecutorService sendParamsExecutor;
+  private final static ClientExecutorServiceFactory clientExcecutorFactory =
+      new ClientExecutorServiceFactory();
+
+  private static class ClientExecutorServiceFactory {
+    private int executorRefCount = 0;
+    private ExecutorService clientExecutor = null;
+    
+    /**
+     * Get Executor on which IPC calls' parameters are sent.
+     * If the internal reference counter is zero, this method
+     * creates the instance of Executor. If not, this method
+     * just returns the reference of clientExecutor.
+     * 
+     * @return An ExecutorService instance
+     */
+    synchronized ExecutorService refAndGetInstance() {
+      if (executorRefCount == 0) {
+        clientExecutor = Executors.newCachedThreadPool(
             new ThreadFactoryBuilder()
             .setDaemon(true)
             .setNameFormat("IPC Parameter Sending Thread #%d")
             .build());
+      }
+      executorRefCount++;
       
+      return clientExecutor;
+    }
+    
+    /**
+     * Cleanup Executor on which IPC calls' parameters are sent.
+     * If reference counter is zero, this method discards the
+     * instance of the Executor. If not, this method
+     * just decrements the internal reference counter.
+     * 
+     * @return An ExecutorService instance if it exists.
+     *   Null is returned if not.
+     */
+    synchronized ExecutorService unrefAndCleanup() {
+      executorRefCount--;
+      assert(executorRefCount >= 0);
+      
+      if (executorRefCount == 0) {
+        clientExecutor.shutdown();
+        try {
+          if (!clientExecutor.awaitTermination(1, TimeUnit.MINUTES)) {
+            clientExecutor.shutdownNow();
+          }
+        } catch (InterruptedException e) {
+          LOG.error("Interrupted while waiting for clientExecutor" +
+              "to stop", e);
+          clientExecutor.shutdownNow();
+        }
+        clientExecutor = null;
+      }
+      
+      return clientExecutor;
+    }
+  };
   
   /**
    * set the ping interval value in configuration
@@ -879,7 +932,8 @@ public class Client {
       }
 
       // Serialize the call to be sent. This is done from the actual
-      // caller thread, rather than the SEND_PARAMS_EXECUTOR thread,
+      // caller thread, rather than the sendParamsExecutor thread,
+      
       // so that if the serialization throws an error, it is reported
       // properly. This also parallelizes the serialization.
       //
@@ -896,7 +950,7 @@ public class Client {
       call.rpcRequest.write(d);
 
       synchronized (sendRpcRequestLock) {
-        Future<?> senderFuture = SEND_PARAMS_EXECUTOR.submit(new Runnable() {
+        Future<?> senderFuture = sendParamsExecutor.submit(new Runnable() {
           @Override
           public void run() {
             try {
@@ -1092,6 +1146,7 @@ public class Client {
     this.fallbackAllowed = conf.getBoolean(CommonConfigurationKeys.IPC_CLIENT_FALLBACK_TO_SIMPLE_AUTH_ALLOWED_KEY,
         CommonConfigurationKeys.IPC_CLIENT_FALLBACK_TO_SIMPLE_AUTH_ALLOWED_DEFAULT);
     this.clientId = StringUtils.getUuidBytes();
+    this.sendParamsExecutor = clientExcecutorFactory.refAndGetInstance();
   }
 
   /**
@@ -1136,6 +1191,8 @@ public class Client {
       } catch (InterruptedException e) {
       }
     }
+    
+    clientExcecutorFactory.unrefAndCleanup();
   }
 
   /**

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ipc/TestIPC.java

@@ -573,6 +573,24 @@ public class TestIPC {
     client.stop();
   }
   
+  @Test(timeout=30000, expected=IOException.class)
+  public void testIpcAfterStopping() throws IOException, InterruptedException {
+    // start server
+    Server server = new TestServer(5, false);
+    InetSocketAddress addr = NetUtils.getConnectAddress(server);
+    server.start();
+
+    // start client
+    Client client = new Client(LongWritable.class, conf);
+    client.call(new LongWritable(RANDOM.nextLong()),
+        addr, null, null, MIN_SLEEP_TIME, 0, conf);
+    client.stop();
+ 
+    // This call should throw IOException.
+    client.call(new LongWritable(RANDOM.nextLong()),
+        addr, null, null, MIN_SLEEP_TIME, 0, conf);
+  }
+
   /**
    * Check that file descriptors aren't leaked by starting
    * and stopping IPC servers.