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From "Andrew McNabb (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-960) Incorrect number of map tasks when there are multiple input files
Date Tue, 30 Jan 2007 19:05:34 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-960?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12468744
] 

Andrew McNabb commented on HADOOP-960:
--------------------------------------

>From an end-user perspective, it seems like the need to split input evenly would be pretty
common.  Especially for a user like myself who uses hadoop-streaming, it would be nice to
 set an "even splits" configuration option rather than subclassing InputFormat.  Since the
rest of the custom code is non-Java, it is a little awkward to write a Java class for this.

Of course, all of this is based on my belief that this would be commonly desirable.  It seems
like something that would be a nice standard feature of the Hadoop toolbox.  I hope the tone
of my request is more clear now.  I really think that this would be a great thing to be available
for everyone.

Thanks again for everything you do.

> Incorrect number of map tasks when there are multiple input files
> -----------------------------------------------------------------
>
>                 Key: HADOOP-960
>                 URL: https://issues.apache.org/jira/browse/HADOOP-960
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: documentation
>    Affects Versions: 0.10.1
>            Reporter: Andrew McNabb
>            Priority: Minor
>
> This problem happens with hadoop-streaming and possibly elsewhere.  If there are 5 input
files, it will create 130 map tasks, even if mapred.map.tasks=128.  The number of map tasks
is incorrectly set to a multiple of the number of files.  (I wrote a much more complete bug
report, but Jira lost it when it had an error, so I'm not in the mood to write it all again)

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