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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-2841) Task level native optimization
Date Sun, 07 Sep 2014 05:45:33 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2841?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14124786#comment-14124786
] 

Hadoop QA commented on MAPREDUCE-2841:
--------------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12667067/mr-2841-merge-4.patch
  against trunk revision d1fa582.

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

    {color:green}+1 tests included{color}.  The patch appears to include 71 new or modified
test files.

      {color:red}-1 javac{color}.  The applied patch generated 1265 javac compiler warnings
(more than the trunk's current 1264 warnings).

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

    {color:red}-1 eclipse:eclipse{color}.  The patch failed to build 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 .

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

Test results: https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/4862//testReport/
Javac warnings: https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/4862//artifact/trunk/patchprocess/diffJavacWarnings.txt
Console output: https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/4862//console

This message is automatically generated.

> Task level native optimization
> ------------------------------
>
>                 Key: MAPREDUCE-2841
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2841
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: task
>         Environment: x86-64 Linux/Unix
>            Reporter: Binglin Chang
>            Assignee: Sean Zhong
>         Attachments: DESIGN.html, MAPREDUCE-2841.v1.patch, MAPREDUCE-2841.v2.patch, MR-2841benchmarks.pdf,
dualpivot-0.patch, dualpivotv20-0.patch, fb-shuffle.patch, hadoop-3.0-mapreduce-2841-2014-7-17.patch,
micro-benchmark.txt, mr-2841-merge-2.txt, mr-2841-merge-3.patch, mr-2841-merge-4.patch, mr-2841-merge.txt
>
>
> I'm recently working on native optimization for MapTask based on JNI. 
> The basic idea is that, add a NativeMapOutputCollector to handle k/v pairs emitted by
mapper, therefore sort, spill, IFile serialization can all be done in native code, preliminary
test(on Xeon E5410, jdk6u24) showed promising results:
> 1. Sort is about 3x-10x as fast as java(only binary string compare is supported)
> 2. IFile serialization speed is about 3x of java, about 500MB/s, if hardware CRC32C is
used, things can get much faster(1G/
> 3. Merge code is not completed yet, so the test use enough io.sort.mb to prevent mid-spill
> This leads to a total speed up of 2x~3x for the whole MapTask, if IdentityMapper(mapper
does nothing) is used
> There are limitations of course, currently only Text and BytesWritable is supported,
and I have not think through many things right now, such as how to support map side combine.
I had some discussion with somebody familiar with hive, it seems that these limitations won't
be much problem for Hive to benefit from those optimizations, at least. Advices or discussions
about improving compatibility are most welcome:) 
> Currently NativeMapOutputCollector has a static method called canEnable(), which checks
if key/value type, comparator type, combiner are all compatible, then MapTask can choose to
enable NativeMapOutputCollector.
> This is only a preliminary test, more work need to be done. I expect better final results,
and I believe similar optimization can be adopt to reduce task and shuffle too. 



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