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From "Gelesh (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-4974) Optimising the LineRecordReader initialize() method
Date Tue, 05 Feb 2013 07:38:13 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-4974?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13571123#comment-13571123
] 

Gelesh commented on MAPREDUCE-4974:
-----------------------------------

[~tlipcon]
I tried out an estimation,on Local, with small data, subtracting the the long value obtained
from System.nanoTime() at the beginning and at the end of the method.

Average time difference was 200 Nano Seconds per each anomic call made to nextKeyValue(),
excluding the very first call, since it involves the object creation.

The total time difference would be 200 * number of Key Value pairs generated per each Map
Task.
                
> Optimising the LineRecordReader initialize() method
> ---------------------------------------------------
>
>                 Key: MAPREDUCE-4974
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4974
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: mrv1, mrv2, performance
>    Affects Versions: 2.0.2-alpha, 0.23.5
>         Environment: Hadoop Linux
>            Reporter: Arun A K
>            Assignee: Gelesh
>              Labels: patch, performance
>             Fix For: 0.20.204.0, 0.24.0
>
>         Attachments: MAPREDUCE-4974.1.patch
>
>   Original Estimate: 1h
>  Remaining Estimate: 1h
>
> I found there is a a scope of optimizing the code, over initialize() if we have compressionCodecs
& codec instantiated only if its a compressed input.
> Mean while Gelesh George Omathil, added if we could avoid the null check of key &
value. This would time save, since for every next key value generation, null check is done.
The intention being to instantiate only once and avoid NPE as well. Hope both could be met
if initialize key & value over  initialize() method. We both have worked on it.

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