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https://issues.apache.org/jira/browse/MAPREDUCE-6488?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14901860#comment-14901860
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He Tianyi commented on MAPREDUCE-6488:
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Went through this again, buffer size has nothing to do with this.
Please mark as Invalid.
> Make buffer size in PipeMapRed configurable
> -------------------------------------------
>
> Key: MAPREDUCE-6488
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6488
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Reporter: He Tianyi
> Assignee: He Tianyi
>
> Default value of buffer size is 128K in {{PipeMapRed}}.
> When mapper input record is large enough that it won't fit in buffer,
> {{MapRunner}} blocks until written. If child process and input reader are
> both slow (due to calculation and decompress), then process of decoding and
> reading will rarely overlap with each other, hurting performance.
> I suppose we should make the buffer size configurable.
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