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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-10681) Remove synchronized blocks from SnappyCodec and ZlibCodec buffering
Date Tue, 17 Jun 2014 20:47:12 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-10681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14034342#comment-14034342
] 

Hadoop QA commented on HADOOP-10681:
------------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12650430/HADOOP-10681.1.patch
  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-common-project/hadoop-common.

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

Test results: https://builds.apache.org/job/PreCommit-HADOOP-Build/4089//testReport/
Console output: https://builds.apache.org/job/PreCommit-HADOOP-Build/4089//console

This message is automatically generated.

> Remove synchronized blocks from SnappyCodec and ZlibCodec buffering
> -------------------------------------------------------------------
>
>                 Key: HADOOP-10681
>                 URL: https://issues.apache.org/jira/browse/HADOOP-10681
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: performance
>    Affects Versions: 2.2.0, 2.4.0, 2.5.0
>            Reporter: Gopal V
>            Assignee: Gopal V
>              Labels: perfomance
>         Attachments: HADOOP-10681.1.patch, compress-cmpxchg-small.png, perf-top-spill-merge.png,
snappy-perf-unsync.png
>
>
> The current implementation of SnappyCompressor spends more time within the java loop
of copying from the user buffer into the direct buffer allocated to the compressor impl, than
the time it takes to compress the buffers.
> !perf-top-spill-merge.png!
> The bottleneck was found to be java monitor code inside SnappyCompressor.
> The methods are neatly inlined by the JIT into the parent caller (BlockCompressorStream::write),
which unfortunately does not flatten out the synchronized blocks.
> !compress-cmpxchg-small.png!
> The loop does a write of small byte[] buffers (each IFile key+value). 
> I counted approximately 6 monitor enter/exit blocks per k-v pair written.



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