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Posted to mapreduce-issues@hadoop.apache.org by "Tsuyoshi OZAWA (JIRA)" <ji...@apache.org> on 2012/12/08 06:09:25 UTC
[jira] [Commented] (MAPREDUCE-4502) Multi-level aggregation with
combining the result of maps per node/rack
[ https://issues.apache.org/jira/browse/MAPREDUCE-4502?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13527037#comment-13527037 ]
Tsuyoshi OZAWA commented on MAPREDUCE-4502:
-------------------------------------------
I'll create subtasks under MAPREDUCE-4525, and attach patches separately to make the review easy.
> Multi-level aggregation with combining the result of maps per node/rack
> -----------------------------------------------------------------------
>
> Key: MAPREDUCE-4502
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4502
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: applicationmaster, mrv2
> Reporter: Tsuyoshi OZAWA
> Assignee: Tsuyoshi OZAWA
> Attachments: design_v2.pdf, MAPREDUCE-4525-pof.diff, speculative_draft.pdf
>
>
> The shuffle costs is expensive in Hadoop in spite of the existence of combiner, because the scope of combining is limited within only one MapTask. To solve this problem, it's a good way to aggregate the result of maps per node/rack by launch combiner.
> This JIRA is to implement the multi-level aggregation infrastructure, including combining per container(MAPREDUCE-3902 is related), coordinating containers by application master without breaking fault tolerance of jobs.
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