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Posted to mapreduce-issues@hadoop.apache.org by "Piotr Kołaczkowski (JIRA)" <ji...@apache.org> on 2012/08/02 11:35:02 UTC
[jira] [Updated] (MAPREDUCE-4506) EofException / 'connection reset
by peer' while copying map output
[ https://issues.apache.org/jira/browse/MAPREDUCE-4506?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Piotr Kołaczkowski updated MAPREDUCE-4506:
------------------------------------------
Attachment: ReduceTask.patch
RamManager.patch
Patch fixing the EofExceptions in shuffleInMemory. Additionally, map output copy connections are taken into try-finally block to assure they are closed properly.
> EofException / 'connection reset by peer' while copying map output
> -------------------------------------------------------------------
>
> Key: MAPREDUCE-4506
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4506
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 1.0.3
> Environment: Ubuntu Linux 12.04 LTS, 64-bit, Java 6 update 33
> Reporter: Piotr Kołaczkowski
> Priority: Minor
> Attachments: RamManager.patch, ReduceTask.patch
>
>
> When running complex mapreduce jobs with many mappers and reducers (e.g. 8 mappers, 8 reducers on a 8 core machine), sometimes the following exceptions pop up in the logs during the shuffle phase:
> {noformat}
> WARN [570516323@qtp-2060060479-164] 2012-07-19 02:50:21,229 TaskTracker.java (line 3894) getMapOutput(attempt_201207161621_0217_m_000071_0,0) failed :
> org.mortbay.jetty.EofException
> at org.mortbay.jetty.HttpGenerator.flush(HttpGenerator.java:787)
> at org.mortbay.jetty.AbstractGenerator$Output.flush(AbstractGenerator.java:568)
> at org.mortbay.jetty.HttpConnection$Output.flush(HttpConnection.java:1005)
> at org.mortbay.jetty.AbstractGenerator$Output.write(AbstractGenerator.java:648)
> at org.mortbay.jetty.AbstractGenerator$Output.write(AbstractGenerator.java:579)
> at org.apache.hadoop.mapred.TaskTracker$MapOutputServlet.doGet(TaskTracker.java:3872)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
> at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
> at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
> at org.apache.hadoop.http.HttpServer$QuotingInputFilter.doFilter(HttpServer.java:835)
> at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
> at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
> at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
> at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
> at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
> at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
> at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
> at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
> at org.mortbay.jetty.Server.handle(Server.java:326)
> at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
> at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
> at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:547)
> at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
> at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
> at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
> at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
> Caused by: java.io.IOException: Connection reset by peer
> at sun.nio.ch.FileDispatcher.write0(Native Method)
> at sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:29)
> at sun.nio.ch.IOUtil.writeFromNativeBuffer(IOUtil.java:72)
> at sun.nio.ch.IOUtil.write(IOUtil.java:43)
> at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:334)
> at org.mortbay.io.nio.ChannelEndPoint.flush(ChannelEndPoint.java:169)
> at org.mortbay.io.nio.SelectChannelEndPoint.flush(SelectChannelEndPoint.java:221)
> at org.mortbay.jetty.HttpGenerator.flush(HttpGenerator.java:721)
> {noformat}
> The problem looks like some network problems at first, however it turns out that hadoop shuffleInMemory sometimes deliberately closes map-output-copy connections just to reopen them a few milliseconds later, because of temporary unavailability of free memory. Because the sending side does not expect this, an exception is thrown. Additionally this leads to wasting resources on the sender side, which does more work than required serving additional requests.
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