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From "Ankit Kamboj (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-4354) Performance improvement with compressor object reinit restriction
Date Mon, 02 Jul 2012 18:48:31 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-4354?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13405234#comment-13405234

Ankit Kamboj commented on MAPREDUCE-4354:

This makes sense. The reinit for LZO should only reset buffers instead of recreating them.
So, I have removed the 'if' condition for GZIP in CodecPool and instead changed reinit logic
in LZOCompressor.
Please find attached the corresponding patch.
> Performance improvement with compressor object reinit restriction
> -----------------------------------------------------------------
>                 Key: MAPREDUCE-4354
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4354
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: performance
>    Affects Versions:
>            Reporter: Ankit Kamboj
>            Priority: Minor
>              Labels: performance
>             Fix For:
>         Attachments: codec_reinit_diff
> HADOOP-5879 patch aimed at picking the conf (instead of default) settings for GzipCodec.
It also involved re-initializing the recycled compressor object. 
> On our performance tests, this re-initialization led to performance degradation of 15%
for LzoCodec because re-initialization for Lzo involves reallocation of buffers. LzoCodec
takes the initial settings from config so it is not necessary to re-initialize it. This patch
checks for the codec class and calls reinit only if the codec class is Gzip. This led to significant
performance improvement of 15% for LzoCodec.

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