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Date: Fri, 22 Aug 2014 23:50:12 +0000 (UTC)
From: "Hadoop QA (JIRA)" <jira@apache.org>
To: mapreduce-issues@hadoop.apache.org
Message-ID: <JIRA.12617132.1353516439368.17724.1408751412825@arcas>
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References: <JIRA.12617132.1353516439368@arcas>
Subject: [jira] [Commented] (MAPREDUCE-4815) FileOutputCommitter.commitJob
 can be very slow for jobs with many output files
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    [ https://issues.apache.org/jira/browse/MAPREDUCE-4815?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14107718#comment-14107718 ] 

Hadoop QA commented on MAPREDUCE-4815:
--------------------------------------

{color:green}+1 overall{color}.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12663778/MAPREDUCE-4815.v7.patch
  against trunk revision .

    {color:green}+1 @author{color}.  The patch does not contain any @author tags.

    {color:green}+1 tests included{color}.  The patch appears to include 3 new or modified test files.

    {color:green}+1 javac{color}.  The applied patch does not increase the total number of javac compiler warnings.

    {color:green}+1 javadoc{color}.  There were no new javadoc warning messages.

    {color:green}+1 eclipse:eclipse{color}.  The patch built with eclipse:eclipse.

    {color:green}+1 findbugs{color}.  The patch does not introduce any new Findbugs (version 2.0.3) warnings.

    {color:green}+1 release audit{color}.  The applied patch does not increase the total number of release audit warnings.

    {color:green}+1 core tests{color}.  The patch passed unit tests in hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core.

    {color:green}+1 contrib tests{color}.  The patch passed contrib unit tests.

Test results: https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/4817//testReport/
Console output: https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/4817//console

This message is automatically generated.

> FileOutputCommitter.commitJob can be very slow for jobs with many output files
> ------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-4815
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4815
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: mrv2
>    Affects Versions: 0.23.3, 2.0.1-alpha, 2.4.1
>            Reporter: Jason Lowe
>            Assignee: Siqi Li
>         Attachments: MAPREDUCE-4815.v3.patch, MAPREDUCE-4815.v4.patch, MAPREDUCE-4815.v5.patch, MAPREDUCE-4815.v6.patch, MAPREDUCE-4815.v7.patch
>
>
> If a job generates many files to commit then the commitJob method call at the end of the job can take minutes.  This is a performance regression from 1.x, as 1.x had the tasks commit directly to the final output directory as they were completing and commitJob had very little to do.  The commit work was processed in parallel and overlapped the processing of outstanding tasks.  In 0.23/2.x, the commit is single-threaded and waits until all tasks have completed before commencing.


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