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https://issues.apache.org/jira/browse/MAPREDUCE-4842?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13531881#comment-13531881
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Alejandro Abdelnur commented on MAPREDUCE-4842:
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I had a cluster setup with trunk to run some gridmix tests (for MAPREDUCE-2454)
and before shutting it down I've done a couple of runs using Asokan's patch.
35 machines cluster. The trace had ~1000 jobs. I've done 2 runs with trunk and
2 runs with the patch.
TRUNK:
Time spent in simulation: 43mins, 31sec
Time spent in simulation: 41mins, 28sec
MAPREDUCE-4842
Time spent in simulation: 39mins, 30sec
Time spent in simulation: 39mins, 25sec
It would worth looking if it could be modified to control the number of merges
being created.
> Shuffle race can hang reducer
> -----------------------------
>
> Key: MAPREDUCE-4842
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4842
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mrv2
> Affects Versions: 2.0.2-alpha, 0.23.5
> Reporter: Jason Lowe
> Assignee: Jason Lowe
> Priority: Blocker
> Attachments: mapreduce-4842.patch, MAPREDUCE-4842.patch,
> MAPREDUCE-4842.patch, MAPREDUCE-4842.patch, MAPREDUCE-4842.patch
>
>
> Saw an instance where the shuffle caused multiple reducers in a job to hang.
> It looked similar to the problem described in MAPREDUCE-3721, where the
> fetchers were all being told to WAIT by the MergeManager but no merge was
> taking place.
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