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Posted to mapreduce-issues@hadoop.apache.org by "Allen Wittenauer (JIRA)" <ji...@apache.org> on 2015/03/16 19:44:42 UTC

[jira] [Updated] (MAPREDUCE-4274) MapOutputBuffer should use native byte order for kvmeta

     [ https://issues.apache.org/jira/browse/MAPREDUCE-4274?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Allen Wittenauer updated MAPREDUCE-4274:
----------------------------------------
    Fix Version/s:     (was: 2.0.0-alpha)
                   2.0.2-alpha

> MapOutputBuffer should use native byte order for kvmeta
> -------------------------------------------------------
>
>                 Key: MAPREDUCE-4274
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4274
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: performance, task
>    Affects Versions: 2.0.0-alpha
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>            Priority: Minor
>             Fix For: 2.0.2-alpha
>
>         Attachments: mapreduce-4274.txt
>
>
> I don't have a benchmark to support this, but this should give a small CPU improvement on the map output buffer: currently, we create {{kvmeta}} as {{ByteBuffer.wrap(kvbuffer).asIntBuffer()}}. According to the javadocs, the resulting int buffer will inherit its byte order from the ByteBuffer it comes from, and the byte buffer defaults to BIG_ENDIAN. Thus, all of our int access to/from the buffer will require byte-swapping.



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