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From "Matei Zaharia (JIRA)" <j...@apache.org>
Subject [jira] Created: (HADOOP-5380) Calls from running tasks to TaskTracker methods sometimes fail and incur a 60s timeout
Date Tue, 03 Mar 2009 05:56:56 GMT
Calls from running tasks to TaskTracker methods sometimes fail and incur a 60s timeout
--------------------------------------------------------------------------------------

                 Key: HADOOP-5380
                 URL: https://issues.apache.org/jira/browse/HADOOP-5380
             Project: Hadoop Core
          Issue Type: Bug
            Reporter: Matei Zaharia


I'm seeing some map tasks in my jobs take 1 minute to commit after they finish the map computation.
On the map side, the output looks like this:

<code>
2009-03-02 21:30:54,384 INFO org.apache.hadoop.metrics.jvm.JvmMetrics: Cannot initialize JVM
Metrics with processName=MAP, sessionId= - already initialized
2009-03-02 21:30:54,437 INFO org.apache.hadoop.mapred.MapTask: numReduceTasks: 800
2009-03-02 21:30:54,437 INFO org.apache.hadoop.mapred.MapTask: io.sort.mb = 300
2009-03-02 21:30:55,493 INFO org.apache.hadoop.mapred.MapTask: data buffer = 239075328/298844160
2009-03-02 21:30:55,494 INFO org.apache.hadoop.mapred.MapTask: record buffer = 786432/983040
2009-03-02 21:31:00,381 INFO org.apache.hadoop.mapred.MapTask: Starting flush of map output
2009-03-02 21:31:07,892 INFO org.apache.hadoop.mapred.MapTask: Finished spill 0
2009-03-02 21:31:07,951 INFO org.apache.hadoop.mapred.TaskRunner: Task:attempt_200903022127_0001_m_003163_0
is done. And is in the process of commiting
2009-03-02 21:32:07,949 INFO org.apache.hadoop.mapred.TaskRunner: Communication exception:
java.io.IOException: Call to /127.0.0.1:50311 failed on local exception: java.nio.channels.ClosedChannelException
	at org.apache.hadoop.ipc.Client.wrapException(Client.java:765)
	at org.apache.hadoop.ipc.Client.call(Client.java:733)
	at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:220)
	at org.apache.hadoop.mapred.$Proxy0.ping(Unknown Source)
	at org.apache.hadoop.mapred.Task$TaskReporter.run(Task.java:525)
	at java.lang.Thread.run(Thread.java:619)
Caused by: java.nio.channels.ClosedChannelException
	at java.nio.channels.spi.AbstractSelectableChannel.register(AbstractSelectableChannel.java:167)
	at java.nio.channels.SelectableChannel.register(SelectableChannel.java:254)
	at org.apache.hadoop.net.SocketIOWithTimeout$SelectorPool.select(SocketIOWithTimeout.java:331)
	at org.apache.hadoop.net.SocketIOWithTimeout.doIO(SocketIOWithTimeout.java:157)
	at org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:155)
	at org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:128)
	at java.io.FilterInputStream.read(FilterInputStream.java:116)
	at org.apache.hadoop.ipc.Client$Connection$PingInputStream.read(Client.java:276)
	at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
	at java.io.BufferedInputStream.read(BufferedInputStream.java:237)
	at java.io.DataInputStream.readInt(DataInputStream.java:370)
	at org.apache.hadoop.ipc.Client$Connection.receiveResponse(Client.java:501)
	at org.apache.hadoop.ipc.Client$Connection.run(Client.java:446)

2009-03-02 21:32:07,953 INFO org.apache.hadoop.mapred.TaskRunner: Task 'attempt_200903022127_0001_m_003163_0'
done.
</code>

In the TaskTracker log, it looks like this:

<code>
2009-03-02 21:31:08,110 WARN org.apache.hadoop.ipc.Server: IPC Server Responder, call ping(attempt_200903022127_0001_m_003163_0)
from 127.0.0.1:56884: output error
2009-03-02 21:31:08,111 INFO org.apache.hadoop.ipc.Server: IPC Server handler 10 on 50311
caught: java.nio.channels.ClosedChannelException
    at sun.nio.ch.SocketChannelImpl.ensureWriteOpen(SocketChannelImpl.java:126)
    at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:324)    at org.apache.hadoop.ipc.Server.channelWrite(Server.java:1195)
    at org.apache.hadoop.ipc.Server.access$1900(Server.java:77)
    at org.apache.hadoop.ipc.Server$Responder.processResponse(Server.java:613)
    at org.apache.hadoop.ipc.Server$Responder.doRespond(Server.java:677)
    at org.apache.hadoop.ipc.Server$Handler.run(Server.java:981)
</code>

Note that the task actually seemed to commit - it didn't get speculatively executed or anything.
However, the job wasn't able to continue until this one task was done. Both parties seem to
think the channel was closed. How does the channel get closed externally? If closing it from
outside is unavoidable, maybe the right thing to do is to set a much lower timeout, because
1 minute delay can be pretty significant for a small job.

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