[jira] [Commented] (MAPREDUCE-3902) MR AM should reuse containers for map tasks

["Jay Finger (Commented) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MAPREDUCE-3902?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13214819#comment-13214819 ] 

Jay Finger commented on MAPREDUCE-3902:
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I haven't read the patch, forgive me if the answer is already there.

Is there a cap on the amount of re-use?  For example, if the container has been in use for more than 1 minute then do not re-use it.

Or to rephrase, what prevents a cluster with a few large jobs from having hogged containers?
                
> MR AM should reuse containers for map tasks
> -------------------------------------------
>
>                 Key: MAPREDUCE-3902
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-3902
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: applicationmaster, mrv2
>            Reporter: Arun C Murthy
>            Assignee: Arun C Murthy
>         Attachments: MAPREDUCE-3902.patch
>
>
> The MR AM is now in a great position to reuse containers across (map) tasks. This is something similar to JVM re-use we had in 0.20.x, but in a significantly better manner:
> # Consider data-locality when re-using containers
> # Consider the new shuffle - ensure that reduces fetch output of the whole container at once (i.e. all maps) 

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