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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-2740) MultipleOutputs in new API creates needless TaskAttemptContexts
Date Wed, 10 Aug 2011 01:27:43 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13082066#comment-13082066
] 

Hudson commented on MAPREDUCE-2740:
-----------------------------------

Integrated in Hadoop-Mapreduce-trunk #751 (See [https://builds.apache.org/job/Hadoop-Mapreduce-trunk/751/])
    MAPREDUCE-2740. MultipleOutputs in new API creates needless TaskAttemptContexts. Contributed
by Todd Lipcon.

todd : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1152875
Files : 
* /hadoop/common/trunk/mapreduce/src/java/org/apache/hadoop/mapreduce/lib/output/MultipleOutputs.java
* /hadoop/common/trunk/mapreduce/CHANGES.txt


> MultipleOutputs in new API creates needless TaskAttemptContexts
> ---------------------------------------------------------------
>
>                 Key: MAPREDUCE-2740
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2740
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>    Affects Versions: 0.23.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>             Fix For: 0.23.0
>
>         Attachments: mr-2740.txt
>
>
> MultipleOutputs.write creates a new TaskAttemptContext, which we've seen to take a significant
amount of CPU. The TaskAttemptContext constructor creates a JobConf, gets current UGI, etc.
I don't see any reason it needs to do this, instead of just creating a single TaskAttemptContext
when the InputFormat is created (or lazily but cached as a member)

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