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https://issues.apache.org/jira/browse/MAPREDUCE-5821?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13960824#comment-13960824
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Hadoop QA commented on MAPREDUCE-5821:
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{color:red}-1 overall{color}. Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12638796/mapreduce-5821.txt
against trunk revision .
{color:green}+1 @author{color}. The patch does not contain any @author
tags.
{color:red}-1 tests included{color}. The patch doesn't appear to include
any new or modified tests.
Please justify why no new tests are needed for this
patch.
Also please list what manual steps were performed to
verify this patch.
{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 1.3.9) 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/4487//testReport/
Console output:
https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/4487//console
This message is automatically generated.
> IFile merge allocates new byte array for every value
> ----------------------------------------------------
>
> Key: MAPREDUCE-5821
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5821
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: performance, task
> Affects Versions: 2.4.1
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Attachments: after-patch.png, before-patch.png, mapreduce-5821.txt,
> mapreduce-5821.txt
>
>
> I wrote a standalone benchmark of the MapOutputBuffer and found that it did a
> lot of allocations during the merge phase. After looking at an allocation
> profile, I found that IFile.Reader.nextRawValue() would always allocate a new
> byte array for every value, so the allocation rate goes way up during the
> merge phase of the mapper. I imagine this also affects the reducer input,
> though I didn't profile that.
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