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From "Yang Yang (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HADOOP-8503) logic difference between old mapred.FileInputFormat and mapreduce.lib.input.FileInputFormat
Date Tue, 12 Jun 2012 02:26:43 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-8503?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Yang Yang updated HADOOP-8503:
------------------------------

    Attachment: 0001-HADOOP-8503-re-enable-mapreduces.job.maps.patch

here is a patch to use the new mapreduce.job.maps  config param

it's the same spirit as the old mapred.map.tasks


I have not tested this since the github source I pulled does not build . Harsh could you please
try this?

Thanks
Yang
                
> logic difference between old mapred.FileInputFormat and mapreduce.lib.input.FileInputFormat
> -------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-8503
>                 URL: https://issues.apache.org/jira/browse/HADOOP-8503
>             Project: Hadoop Common
>          Issue Type: Bug
>    Affects Versions: 0.20.0
>            Reporter: Yang Yang
>            Priority: Minor
>         Attachments: 0001-HADOOP-8503-re-enable-mapreduces.job.maps.patch
>
>
> in the old mapred.FileInputFormat.getSplits(JobConf, int) 
>         long splitSize = computeSplitSize(goalSize, minSize, blockSize);
> so we could control splitSize with the goalSize, which is controlled by mapred.map.tasks

> in the new code, mapreduces.lib.input.FileInputFormat
>         long splitSize = computeSplitSize(blockSize, minSize, maxSize);
> i.e. we don't have goal size anymore, furthermore,
> the implementation of computeSplitSize() no longer makes sense:
>     return Math.max(minSize, Math.min(maxSize, blockSize));
> since we assume that maxSize is always bigger than minSize, the above line is equivalent
to  just
> return Math.min(maxSize, blockSize), so minSize is useless 

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