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Posted to mapreduce-issues@hadoop.apache.org by "Hadoop QA (JIRA)" <ji...@apache.org> on 2011/02/27 23:00:38 UTC
[jira] Commented: (MAPREDUCE-2047) reduce overhead of
findSpeculativeTask
[ https://issues.apache.org/jira/browse/MAPREDUCE-2047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13000050#comment-13000050 ]
Hadoop QA commented on MAPREDUCE-2047:
--------------------------------------
-1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12457218/2047.3.patch
against trunk revision 1074251.
+1 @author. The patch does not contain any @author tags.
+1 tests included. The patch appears to include 3 new or modified tests.
+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 does not introduce any 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 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/68//testReport/
Findbugs warnings: https://hudson.apache.org/hudson/job/PreCommit-MAPREDUCE-Build/68//artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Console output: https://hudson.apache.org/hudson/job/PreCommit-MAPREDUCE-Build/68//console
This message is automatically generated.
> reduce overhead of findSpeculativeTask
> --------------------------------------
>
> Key: MAPREDUCE-2047
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2047
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: jobtracker
> Environment: hadoop-20 with HADOOP-2141
> Reporter: Joydeep Sen Sarma
> Assignee: Joydeep Sen Sarma
> Attachments: 2047.3.patch, mapreduce-2047.1.patch, mapreduce-2047.2.patch
>
>
> We are bottlenecked (in the JT) on the jobtracker lock and calls to findSpeculativeTask frequently show up as one of the top routines (by time) called holding this lock.
> this routine calls canBeSpeculated() and hasRunOnMachine() for each task in a candidate job. Both these routines are reasonably expensive when invoked repeatedly for thousands of tasks. The top candidates for speculation from a job only need to be refreshed periodically (and not once every heartbeat) - and we can can avoid most of these invocations this way.
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