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https://issues.apache.org/jira/browse/MAPREDUCE-5168?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13649954#comment-13649954
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Vinod Kumar Vavilapalli commented on MAPREDUCE-5168:
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+1, harmless patch and looks good..
I'm surprised this is the only 'leak', there may be others we can find by
digging through the code. Been a while since this code is touched..
Can commit it in a while or you can go ahead too. Tx.
> Reducer can OOM during shuffle because on-disk output stream not released
> -------------------------------------------------------------------------
>
> Key: MAPREDUCE-5168
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5168
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mrv2
> Affects Versions: 0.23.7, 2.0.5-beta
> Reporter: Jason Lowe
> Assignee: Jason Lowe
> Priority: Critical
> Attachments: MAPREDUCE-5168-branch-0.23.patch, MAPREDUCE-5168.patch
>
>
> If a reducer needs to shuffle a map output to disk, it opens an output stream
> and writes the data to disk. However it does not release the reference to
> the output stream within the MapOutput, and the output stream can have a 128K
> buffer attached to it. If enough of these on-disk outputs are queued up
> waiting to be merged, it can cause the reducer to OOM during the shuffle
> phase. In one case I saw there were 1200 on-disk outputs queued up to be
> merged, leading to an extra 150MB of pressure on the heap due to the output
> stream buffers that were no longer necessary.
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