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From "Hua xu (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HADOOP-9684) the initialization or missed may be for org.apache.ipc.Client$Connection
Date Tue, 02 Jul 2013 13:19:25 GMT
Hua xu created HADOOP-9684:
------------------------------

             Summary: the initialization or missed may be for org.apache.ipc.Client$Connection
                 Key: HADOOP-9684
                 URL: https://issues.apache.org/jira/browse/HADOOP-9684
             Project: Hadoop Common
          Issue Type: Bug
          Components: ipc
    Affects Versions: 0.21.0, 1.0.3
            Reporter: Hua xu


Today, we see that a TaskTracer has keeped throwing the same exception in our production environment.it
is that:

2013-07-01 18:41:40,023 INFO org.apache.hadoop.mapred.TaskTracker: addFreeSlot : current free
slots : 7
2013-07-01 18:41:43,026 INFO org.apache.hadoop.mapred.TaskTracker: LaunchTaskAction (registerTask):
attempt_201208241212_27521_m_000002_3 task's state:UNASSIGNED
2013-07-01 18:41:43,026 INFO org.apache.hadoop.mapred.TaskTracker: Trying to launch : attempt_201208241212_27521_m_000002_3
which needs 1 slots
2013-07-01 18:41:43,026 INFO org.apache.hadoop.mapred.TaskTracker: In TaskLauncher, current
free slots : 7 and trying to launch attempt_201208241212_27521_m_000002_3 which needs 1 slots
2013-07-01 18:41:43,026 INFO org.apache.hadoop.mapreduce.server.tasktracker.Localizer: User-directories
for the user sds are already initialized on this TT. Not doing anything.
2013-07-01 18:41:43,029 WARN org.apache.hadoop.mapred.TaskTracker: Error initializing attempt_201208241212_27521_m_000002_3:
java.lang.NullPointerException

2013-07-01 18:41:43,029 ERROR org.apache.hadoop.mapred.TaskStatus: Trying to set finish time
for task attempt_201208241212_27521_m_000002_3 when no start time is set, stackTrace is :
java.lang.Exception
	at org.apache.hadoop.mapred.TaskStatus.setFinishTime(TaskStatus.java:195)
	at org.apache.hadoop.mapred.MapTaskStatus.setFinishTime(MapTaskStatus.java:51)
	at org.apache.hadoop.mapred.TaskTracker$TaskInProgress.kill(TaskTracker.java:2937)
	at org.apache.hadoop.mapred.TaskTracker.startNewTask(TaskTracker.java:2255)
	at org.apache.hadoop.mapred.TaskTracker$TaskLauncher.run(TaskTracker.java:2212)

  Then, we view the log files of the TaskTracker,and find that the TaskTracker throwed Several
OutOfMemoryError: Java heap space about ten days ago. after that, the TaskTracker has still
throws the exception:


2013-06-22 12:39:42,296 INFO org.apache.hadoop.mapred.TaskTracker: LaunchTaskAction (registerTask):
attempt_201208241212_26088_m_000043_1 task's state:UNASSIGNED
2013-06-22 12:39:42,296 INFO org.apache.hadoop.mapred.TaskTracker: Trying to launch : attempt_201208241212_26088_m_000043_1
which needs 1 slots
2013-06-22 12:39:42,296 INFO org.apache.hadoop.mapred.TaskTracker: In TaskLauncher, current
free slots : 7 and trying to launch attempt_201208241212_26088_m_000043_1 which needs 1 slots
2013-06-22 12:39:42,296 INFO org.apache.hadoop.mapreduce.server.tasktracker.Localizer: Initializing
user sds on this TT.
2013-06-22 12:39:42,300 WARN org.apache.hadoop.mapred.TaskTracker: Error initializing attempt_201208241212_26088_m_000043_1:
java.lang.NullPointerException
	at org.apache.hadoop.ipc.Client$Connection.sendParam(Client.java:630)
	at org.apache.hadoop.ipc.Client.call(Client.java:886)
	at org.apache.hadoop.ipc.WritableRpcEngine$Invoker.invoke(WritableRpcEngine.java:198)
	at $Proxy5.getFileInfo(Unknown Source)
	at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:82)
	at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:59)
	at $Proxy5.getFileInfo(Unknown Source)
	at org.apache.hadoop.hdfs.DFSClient.getFileInfo(DFSClient.java:850)
	at org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus(DistributedFileSystem.java:620)
	at org.apache.hadoop.mapred.TaskTracker.localizeJobTokenFile(TaskTracker.java:3984)
	at org.apache.hadoop.mapred.TaskTracker.localizeJobFiles(TaskTracker.java:1036)
	at org.apache.hadoop.mapred.TaskTracker.localizeJob(TaskTracker.java:977)
	at org.apache.hadoop.mapred.TaskTracker.startNewTask(TaskTracker.java:2247)
	at org.apache.hadoop.mapred.TaskTracker$TaskLauncher.run(TaskTracker.java:2212)

2013-06-22 12:39:42,300 ERROR org.apache.hadoop.mapred.TaskStatus: Trying to set finish time
for task attempt_201208241212_26088_m_000043_1 when no start time is set, stackTrace is :
java.lang.Exception
	at org.apache.hadoop.mapred.TaskStatus.setFinishTime(TaskStatus.java:195)
	at org.apache.hadoop.mapred.MapTaskStatus.setFinishTime(MapTaskStatus.java:51)
	at org.apache.hadoop.mapred.TaskTracker$TaskInProgress.kill(TaskTracker.java:2937)
	at org.apache.hadoop.mapred.TaskTracker.startNewTask(TaskTracker.java:2255)
	at org.apache.hadoop.mapred.TaskTracker$TaskLauncher.run(TaskTracker.java:2212)
  
  Since then, the TaskTracker has not completed any task.we can find the property of Connection
-out is null from the above exeption,and it is caused by the failure of method setupIOstream()
in the class org.apache.ipc.Client$Connection.anyway, the instance of Connection is not null
and cached by the org.apache.ipc.Client.We guess that it throwed a OutOfMemoryError when a
thread called the setupIOstream() because of RPC, so that some properties of the Connection
are null, and throw NullPointerException when the Connection are accessed by other threads,which
is fron the cache.It must be correct to make sure that the instance of Connection could only
be cached after initialized successfully. We fixed the Method getConnection() to guarantee
the semantic:

private Connection getConnection(InetSocketAddress addr,
                                   Class<?> protocol,
                                   UserGroupInformation ticket,
                                   Call call)
                                   throws IOException, InterruptedException {
    if (!running.get()) {
      // the client is stopped
      throw new IOException("The client is stopped");
    }
    Connection connection;
    /* we could avoid this allocation for each RPC by having a  
     * connectionsId object and with set() method. We need to manage the
     * refs for keys in HashMap properly. For now its ok.
     */
    ConnectionId remoteId = new ConnectionId(addr, protocol, ticket);
    do {
      synchronized (connections) {
        connection = connections.get(remoteId);
        if (connection == null) {
          connection = new Connection(remoteId);
          
 +         connection.setupIOstreams();
          
          connections.put(remoteId, connection);
        }
      }
    } while (!connection.addCall(call));
    
    //we don't invoke the method below inside "synchronized (connections)"
    //block above. The reason for that is if the server happens to be slow,
    //it will take longer to establish a connection and that will slow the
    //entire system down.
-    connection.setupIOstreams();
    
    return connection;
  }

  On the other hand, we also simulate this scenario.Firstly, one thread create the Connection
instance and throw OutOfMemoryError when it call connection.setupIOstreams().after that, the
other thread start call RPC through by the instance and it keeps throwing the same exceptions


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