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From "Jerry Chen (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (MAPREDUCE-4961) Map reduce running local should also go through ShuffleConsumerPlugin for enabling different MergeManager implementations
Date Fri, 25 Jan 2013 07:33:12 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-4961?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jerry Chen updated MAPREDUCE-4961:
----------------------------------

    Issue Type: Bug  (was: Improvement)
    
> Map reduce running local should also go through ShuffleConsumerPlugin for enabling different
MergeManager implementations
> -------------------------------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-4961
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4961
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>    Affects Versions: trunk
>            Reporter: Jerry Chen
>   Original Estimate: 72h
>  Remaining Estimate: 72h
>
> MAPREDUCE-4049 provide the ability for pluggable Shuffle and MAPREDUCE-4080 extends Shuffle
to be able to provide different MergeManager implementations. 
> While using these pluggable features, I find that when a map reduce is running locally,
a RawKeyValueIterator was returned directly from a static call of Merge.merge, which break
the assumption that the Shuffle may provide different merge methods although there is no copy
phase for this situation.
> The use case is when I am implementating a hash-based MergeManager, we don't need sort
in map side, while when running the map reduce locally, the hash-based MergeManager will have
no chance to be used as it goes directly to Merger.merge. This makes the pluggable Shuffle
and MergeManager incomplete.
> So we need to move the code calling Merger.merge from Reduce Task to ShuffleConsumerPlugin
implementation, so that the Suffle implementation can decide how to do the merge and return
corresponding iterator.

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