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From "Vinod K V (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-1184) mapred.reduce.slowstart.completed.maps is too high by default
Date Thu, 05 Nov 2009 05:53:32 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1184?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12773792#action_12773792
] 

Vinod K V commented on MAPREDUCE-1184:
--------------------------------------

This is a per-job configuration. And all the issues quoted above seem to be characteristic
of the job in question. As such, no default value will ever cater to all the job characteristics.
Why not let it be and change site-specific, job-specific configuration?

> mapred.reduce.slowstart.completed.maps is too high by default
> -------------------------------------------------------------
>
>                 Key: MAPREDUCE-1184
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1184
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>            Reporter: Allen Wittenauer
>
> By default, this value is set to 5%.  I believe for most real world situations the code
isn't efficient enough to be set this low.  This should be higher, probably around the 50%
mark, especially given the predominance of non-FIFO schedulers.

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