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From "Owen O'Malley (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-93) allow minimum split size configurable
Date Fri, 17 Mar 2006 22:04:58 GMT
    [ http://issues.apache.org/jira/browse/HADOOP-93?page=comments#action_12370894 ] 

Owen O'Malley commented on HADOOP-93:
-------------------------------------

>From what I've seen, it is always 32M fragments, but that is still 300k input splits/maps,
which is a lot. We'd like to be able to drop that by an order of magnitude. (I think in this
case that the input splitter never finished, so we don't know.)

> allow minimum split size configurable
> -------------------------------------
>
>          Key: HADOOP-93
>          URL: http://issues.apache.org/jira/browse/HADOOP-93
>      Project: Hadoop
>         Type: Bug
>     Reporter: Hairong Kuang
>  Attachments: hadoop-93.fix
>
> The current default split size is the size of a block (32M) and a SequenceFile sets it
to be SequenceFile.SYNC_INTERVAL(2K). We currently have a Map/Reduce application working on
crawled docuements. Its input data consists of 356 sequence files, each of which is of a size
around 30G. A jobtracker takes forever to launch the job because it needs to generate 356*30G/2K
map tasks!
> The proposed solution is to let the minimum split size configurable so that the programmer
can control the number of tasks to generate.

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