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https://issues.apache.org/jira/browse/MAPREDUCE-1248?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12885598#action_12885598
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Hadoop QA commented on MAPREDUCE-1248:
--------------------------------------

-1 overall.  Here are the results of testing the latest attachment 
  
http://issues.apache.org/jira/secure/attachment/12426511/MAPREDUCE-1248-v1.0.patch
  against trunk revision 960808.

    +1 @author.  The patch does not contain any @author tags.

    -1 tests included.  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.

    +1 javadoc.  The javadoc tool did not generate any warning messages.

    -1 javac.  The patch appears to cause tar ant target to fail.

    +1 findbugs.  The patch does not introduce any new Findbugs warnings.

    +1 release audit.  The applied patch does not increase the total number of 
release audit warnings.

    +1 core tests.  The patch passed core unit tests.

    -1 contrib tests.  The patch failed contrib unit tests.

Test results: 
http://hudson.zones.apache.org/hudson/job/Mapreduce-Patch-h6.grid.sp2.yahoo.net/592/testReport/
Findbugs warnings: 
http://hudson.zones.apache.org/hudson/job/Mapreduce-Patch-h6.grid.sp2.yahoo.net/592/artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html
Checkstyle results: 
http://hudson.zones.apache.org/hudson/job/Mapreduce-Patch-h6.grid.sp2.yahoo.net/592/artifact/trunk/build/test/checkstyle-errors.html
Console output: 
http://hudson.zones.apache.org/hudson/job/Mapreduce-Patch-h6.grid.sp2.yahoo.net/592/console

This message is automatically generated.

> Redundant memory copying in StreamKeyValUtil
> --------------------------------------------
>
>                 Key: MAPREDUCE-1248
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1248
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: contrib/streaming
>            Reporter: Ruibang He
>            Priority: Minor
>         Attachments: MAPREDUCE-1248-v1.0.patch
>
>
> I found that when MROutputThread collecting the output of  Reducer, it calls 
> StreamKeyValUtil.splitKeyVal() and two local byte-arrays are allocated there 
> for each line of output. Later these two byte-arrays are passed to variable 
> key and val. There are twice memory copying here, one is the 
> System.arraycopy() method, the other is inside key.set() / val.set().
> This causes double times of memory copying for the whole output (may lead to 
> higher CPU consumption), and frequent temporay object allocation.

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