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https://issues.apache.org/jira/browse/MAPREDUCE-6689?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15271812#comment-15271812
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Haibo Chen commented on MAPREDUCE-6689:
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We saw an instance of the similar problem previously as well, but we were not
able to investigate this in great details because logs were overridden quickly.
Do you still have the MR AM logs?
MAPREDUCE-6514 has already been created to fix the issue of not updating the
requests in clearAllPendingReduceRequests().
> MapReduce job can infinitely increasing number of reducer resource requests
> ---------------------------------------------------------------------------
>
> Key: MAPREDUCE-6689
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6689
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Reporter: Wangda Tan
> Assignee: Wangda Tan
> Priority: Blocker
>
> We have seen this issue from one of our clusters: when running terasort
> map-reduce job, some mappers failed after reducer started, and then MR AM
> tries to preempt reducers to schedule these failed mappers.
> After that, MR AM enters an infinite loop, for every
> RMContainerAllocator#heartbeat run, it:
> - In {{preemptReducesIfNeeded}}, it cancels all scheduled reducer requests.
> (total scheduled reducers = 1024)
> - Then, in {{scheduleReduces}}, it ramps up all reducers (total = 1024).
> As a result, we can see total #requested-containers increased 1024 for every
> MRAM-RM heartbeat (1 sec per heartbeat). The AM is hanging for 18+ hours, so
> we get 18 * 3600 * 1024 ~ 66M+ requested containers in RM side.
> And this bug also triggered YARN-4844, which makes RM stop scheduling
> anything.
> Thanks to [~sidharta-s] for helping with analysis.
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