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https://issues.apache.org/jira/browse/MAPREDUCE-956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12753647#action_12753647
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Arun C Murthy commented on MAPREDUCE-956:
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I can see hte appeal of this, but we should remember that there are
applications where merge is a significant part of the reduce runtime e.g.
petasort's merge was _huge_.
> Shuffle should be broken down to only two phases (copy/reduce) instead of
> three (copy/sort/reduce)
> --------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-956
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-956
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: task
> Affects Versions: 0.21.0
> Reporter: Jothi Padmanabhan
>
> For the progress calculations and displaying on the UI, shuffle, in its
> current form, is decomposed into three phases (copy/sort/reduce). Actually,
> the sort phase is no longer applicable. I think we should just reduce the
> number of phases to two and assign 50% weight-age to each of copy and reduce
> phases. Thoughts?
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