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From "Chris Douglas (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-830) Providing BZip2 splitting support for Text data
Date Sun, 30 Aug 2009 21:49:34 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-830?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12749333#action_12749333

Chris Douglas commented on MAPREDUCE-830:

(related comments in HADOOP-4012)
* Though it's not changed in bzip, since {{getEnd}} is part of the API, it should be called
in {{LineRecordReader}}.
* Since the codec has state, the API demands that {{LineRecordReader}} synchronize on the
codec before creating a splittable stream and calling {{getStart}} and {{getEnd}} to avoid
race conditions (unless a better solution is found in HADOOP-4012)
* The default dir for unit tests is usually "/tmp", not "."

> Providing BZip2 splitting support for Text data
> -----------------------------------------------
>                 Key: MAPREDUCE-830
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-830
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>    Affects Versions: 0.21.0
>            Reporter: Abdul Qadeer
>            Assignee: Abdul Qadeer
>             Fix For: 0.21.0
>         Attachments: MapReduce-830-version1.patch
> HADOOP-4012 (https://issues.apache.org/jira/browse/HADOOP-4012) is providing support
to handle BZip2 compressed data such that the input compressed file is split at arbitrary
points.  This JIRA uses that functionality in LineRecordReader.  The benefit of this work
is that, if user provides compressed BZip2 Text data, it will be split by Hadoop and hence
will be processed by multiple mappers.  So BZip2 compressed data will be able to fully utilize
the cluster power.  Currently BZip2 compressed Text file goes to one mapper and is not split.
 So the enhancement in this JIRA provides splitting support  and a considerable performance

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