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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-5861) finishedSubMaps field in LocalContainerLauncher does not need to be volatile
Date Tue, 20 May 2014 15:38:47 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-5861?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14003473#comment-14003473
] 

Hudson commented on MAPREDUCE-5861:
-----------------------------------

FAILURE: Integrated in Hadoop-Mapreduce-trunk #1780 (See [https://builds.apache.org/job/Hadoop-Mapreduce-trunk/1780/])
MAPREDUCE-5861. finishedSubMaps field in LocalContainerLauncher does not need to be volatile.
(Contributed by Tsuyoshi OZAWA) (junping_du: http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1594795)
* /hadoop/common/trunk/hadoop-mapreduce-project/CHANGES.txt
* /hadoop/common/trunk/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapred/LocalContainerLauncher.java


> finishedSubMaps field in LocalContainerLauncher does not need to be volatile
> ----------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-5861
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5861
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>            Reporter: Ted Yu
>            Assignee: Tsuyoshi OZAWA
>            Priority: Minor
>             Fix For: 2.5.0
>
>         Attachments: MAPREDUCE-5861.1.patch, MAPREDUCE-5861.2.patch
>
>
> Around line 374:
> {code}
>           if (++finishedSubMaps == numMapTasks) {
>             doneWithMaps = true;
>           }
> {code}
> The increment of finishedSubMaps is not atomic.
> See the answer to http://stackoverflow.com/questions/9749746/what-is-the-difference-of-atomic-volatile-synchronize
.
> AtomicInteger can be used to achieve atomicity.



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