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From "Kan Zhang (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-5380) Calls from running tasks to TaskTracker methods sometimes fail and incur a 60s timeout
Date Tue, 04 Jan 2011 22:02:47 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-5380?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12977487#action_12977487
] 

Kan Zhang commented on HADOOP-5380:
-----------------------------------

Just one quick observation. Currently, to close a connection that has already been set up,
all other threads would set the shouldCloseConnection flag by calling markClosed() and the
actual close() (cleanup) is done by the receiver thread itself. Your current patch simply
interrupts this thread. This may cause it to bypass the cleanup.

> 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 Common
>          Issue Type: Bug
>    Affects Versions: 0.20.1
>            Reporter: Matei Zaharia
>         Attachments: HADOOP-5380.Y.20.branch.patch
>
>
> 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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