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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-2541) Race Condition in IndexCache(readIndexFileToCache,removeMap) causes value of totalMemoryUsed corrupt, which may cause TaskTracker continue throw Exception
Date Sat, 28 May 2011 23:00:47 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2541?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13040690#comment-13040690
] 

Hadoop QA commented on MAPREDUCE-2541:
--------------------------------------

-1 overall.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12480750/MAPREDUCE-2541.patch
  against trunk revision 1128394.

    +1 @author.  The patch does not contain any @author tags.

    -1 tests included.  The patch doesn't appear to include any new or modified tests.
                        Please justify why no new tests are needed for this patch.
                        Also please list what manual steps were performed to verify this patch.

    +1 javadoc.  The javadoc tool did not generate any warning messages.

    +1 javac.  The applied patch does not increase the total number of javac compiler warnings.

    -1 findbugs.  The patch appears to introduce 1 new Findbugs (version 1.3.9) warnings.

    +1 release audit.  The applied patch does not increase the total number of release audit
warnings.

    -1 core tests.  The patch failed these core unit tests:
                  org.apache.hadoop.cli.TestMRCLI
                  org.apache.hadoop.tools.TestHadoopArchives
                  org.apache.hadoop.tools.TestHarFileSystem

    -1 contrib tests.  The patch failed contrib unit tests.

    +1 system test framework.  The patch passed system test framework compile.

Test results: https://builds.apache.org/hudson/job/PreCommit-MAPREDUCE-Build/319//testReport/
Findbugs warnings: https://builds.apache.org/hudson/job/PreCommit-MAPREDUCE-Build/319//artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Console output: https://builds.apache.org/hudson/job/PreCommit-MAPREDUCE-Build/319//console

This message is automatically generated.

> Race Condition in IndexCache(readIndexFileToCache,removeMap) causes value of totalMemoryUsed
corrupt, which may cause TaskTracker continue throw Exception
> ----------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-2541
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2541
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: tasktracker
>    Affects Versions: 0.20.1, 0.21.0, 0.22.0, 0.23.0
>         Environment: all
>            Reporter: Binglin Chang
>            Priority: Critical
>         Attachments: MAPREDUCE-2541.patch
>
>
> The race condition goes like this:
> Thread1: readIndexFileToCache()  totalMemoryUsed.addAndGet(newInd.getSize())
> Thread2: removeMap() totalMemoryUsed.addAndGet(-info.getSize());
> When SpillRecord is being read from fileSystem, client kills the job, info.getSize()
equals 0, so in fact totalMemoryUsed is not reduced, but after thread1 finished reading SpillRecord,
it adds the real index size to totalMemoryUsed, which makes the value of totalMemoryUsed wrong(larger).
> When this value(totalMemoryUsed) exceeds totalMemoryAllowed (this usually happens when
a vary large job with vary large reduce number is killed by the user, probably because the
user sets a wrong reduce number by mistake), and actually indexCache has not cache anything,
freeIndexInformation() will throw exception constantly.
> A quick fix for this issue is to make removeMap() do nothing, let freeIndexInformation()
do this job only.

--
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