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https://issues.apache.org/jira/browse/MAPREDUCE-1342?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12802161#action_12802161
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Hemanth Yamijala commented on MAPREDUCE-1342:
---------------------------------------------
I verified the changes in the patch for Branch 0.21 to see the shared data
structures are accessed under the JT lock. Also the patch for 21 seems similar
to the patch for trunk. Will commit the changes to branch 0.21 to unblock other
patches.
> Potential JT deadlock in faulty TT tracking
> -------------------------------------------
>
> Key: MAPREDUCE-1342
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1342
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: jobtracker
> Affects Versions: 0.20.1
> Reporter: Todd Lipcon
> Assignee: Amareshwari Sriramadasu
> Fix For: 0.21.0
>
> Attachments: cycle0.png, mapreduce-1342-1.patch,
> mapreduce-1342-2.patch, patch-1342-0.21.txt, patch-1342-1.txt,
> patch-1342-2-ydist.txt, patch-1342-2.txt, patch-1342-3-ydist.txt,
> patch-1342-3.txt, patch-1342-ydist.txt, patch-1342.txt
>
>
> JT$FaultyTrackersInfo.incrementFaults first locks potentiallyFaultyTrackers,
> and then calls blackListTracker, which calls removeHostCapacity, which locks
> JT.taskTrackers
> On the other hand, JT.blacklistedTaskTrackers() locks taskTrackers, then
> calls faultyTrackers.isBlacklisted() which goes on to lock
> potentiallyFaultyTrackers.
> I haven't produced such a deadlock, but the lock ordering here is inverted
> and therefore could deadlock.
> Not sure if this goes back to 0.21 or just in trunk.
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