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https://issues.apache.org/jira/browse/MAPREDUCE-956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12753149#action_12753149
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Jothi Padmanabhan commented on MAPREDUCE-956:
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True, we do have a final merge before feeding the reducer. However, assigning
33% of progress for this one final merge does not seem to be correct. In cases
where the number of files at that time is < io.sort.factor, this final merge
does not even occur, we start feeding the reducer straight away. Also, since we
have merges happening during shuffle phase as well, I was just proposing that
we delineate as
Shuffle (50%)
Final Merge + Reduce (50%)
> 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 the sort phase is no longer applicable.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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