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Posted to mapreduce-issues@hadoop.apache.org by "Allen Wittenauer (JIRA)" <ji...@apache.org> on 2009/10/22 00:50:59 UTC

[jira] Commented: (MAPREDUCE-1129) Assign multiple Map and Reduce tasks in Fairscheduler

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1129?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12768500#action_12768500 ] 

Allen Wittenauer commented on MAPREDUCE-1129:
---------------------------------------------

We're seeing exactly the same issue.

> Assign multiple Map and Reduce tasks in Fairscheduler
> -----------------------------------------------------
>
>                 Key: MAPREDUCE-1129
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1129
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: contrib/fair-share
>    Affects Versions: 0.20.1
>            Reporter: Scott Chen
>
> In Hadoop-0.20, the period of heartbeat becomes much longer. 
> Fairscheduler assigns at most one Map and one Reduce task per heartbeat.
> This makes the cluster become very inefficient. Often time only half of the slots are used.
> One idea is that we make Fairscheduler detect this situation (cluster under used) and scheduler more tasks in a heartbeat.
> Thoughts?

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