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https://issues.apache.org/jira/browse/MAPREDUCE-1436?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12836438#action_12836438
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Matei Zaharia commented on MAPREDUCE-1436:
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You're right Todd, it looks like with the new job retiring process, the JT lock
is always grabbed before the fair scheduler lock, and neither of the two
deadlocks I pointed out could occur. MAPREDUCE-870 seems to be in both trunk
and 0.21, so everything should be fine. However, the issue in MAPREDUCE-1499
does affect Hadoop 0.20 and should be fixed.
> Deadlock in preemption code in fair scheduler
> ---------------------------------------------
>
> Key: MAPREDUCE-1436
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1436
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: contrib/fair-share
> Affects Versions: 0.21.0, 0.22.0
> Reporter: Matei Zaharia
> Assignee: Matei Zaharia
> Priority: Blocker
> Attachments: deadlock.png, mapreduce-1436-v2.patch,
> mapreduce-1436.patch
>
>
> In testing the fair scheduler with preemption, I found a deadlock between
> updatePreemptionVariables and some code in the JobTracker. This was found
> while testing a backport of the fair scheduler to Hadoop 0.20, but it looks
> like it could also happen in trunk and 0.21. Details are in a comment below.
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