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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-2116) optimize getTasksToKill to reduce JobTracker contention
Date Tue, 01 Mar 2011 09:15:37 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2116?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13000789#comment-13000789
] 

Hadoop QA commented on MAPREDUCE-2116:
--------------------------------------

-1 overall.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12472135/2116.5.patch
  against trunk revision 1075670.

    +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 patch appears to cause tar ant target to fail.

    -1 findbugs.  The patch appears to cause Findbugs (version 1.3.9) to fail.

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

    +1 core tests.  The patch passed core unit tests.

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

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

Test results: https://hudson.apache.org/hudson/job/PreCommit-MAPREDUCE-Build/104//testReport/
Console output: https://hudson.apache.org/hudson/job/PreCommit-MAPREDUCE-Build/104//console

This message is automatically generated.

> optimize getTasksToKill to reduce JobTracker contention
> -------------------------------------------------------
>
>                 Key: MAPREDUCE-2116
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2116
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: jobtracker
>            Reporter: Joydeep Sen Sarma
>            Assignee: Joydeep Sen Sarma
>         Attachments: 2116.1.patch, 2116.2.patch, 2116.3.patch, 2116.4.patch, 2116.5.patch,
getTaskToKill.JPG
>
>
> getTasksToKill shows up as one of the top routines holding the JT lock. Specifically,
the translation from attemptid to tip is very expensive:
>         at java.util.TreeMap.getEntry(TreeMap.java:328)
>         at java.util.TreeMap.get(TreeMap.java:255)
>         at org.apache.hadoop.mapred.TaskInProgress.shouldClose(TaskInProgress.java:500)
>         at org.apache.hadoop.mapred.JobTracker.getTasksToKill(JobTracker.java:3464)
>           locked <0x00002aab6ebb6640> (a org.apache.hadoop.mapred.JobTracker)
>         at org.apache.hadoop.mapred.JobTracker.heartbeat(JobTracker.java:3181)
> this seems like an avoidable expense since the tip for a given attempt is fixed (and
one should not need a map lookup to find the association). on a different note - not clear
to me why TreeMaps are in use here (i didn't find any iteration over these maps). any background
info on why things are arranged the way they are would be useful.

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