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Posted to mapreduce-issues@hadoop.apache.org by "Luke Lu (JIRA)" <ji...@apache.org> on 2011/05/17 20:23:49 UTC

[jira] [Commented] (MAPREDUCE-2504) MR 279: race in JobHistoryEventHandler stop

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13034941#comment-13034941 ] 

Luke Lu commented on MAPREDUCE-2504:
------------------------------------

The code looks correct but a bit too tricky for application (vs library) code. Need a bit more comment about ensuring all remaining events are handled in the event of interrupt from the stop method. I think we should probably refactor the event queue into the common event package and add some unit tests for it.

> MR 279: race in JobHistoryEventHandler stop 
> --------------------------------------------
>
>                 Key: MAPREDUCE-2504
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2504
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: mrv2
>            Reporter: Siddharth Seth
>            Assignee: Siddharth Seth
>             Fix For: 0.23.0
>
>         Attachments: MR2504.patch
>
>
> The condition to stop the eventHandling thread currently requires it to be 'stopped' AND interrupted. If an interrupt arrives after a take, but before handleEvent is called - the interrupt status ends up being handled by hadoop.util.Shell.runCommand() - which ignores it (and in the process resets the flag).
> The eventHandling thread subsequently hangs on eventQueue.take()
> This currently randomly fails unit tests - and can hang MR AMs.

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