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From "Junping Du (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-5583) Ability to limit running map and reduce tasks
Date Tue, 03 Mar 2015 02:18:07 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-5583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14344331#comment-14344331

Junping Du commented on MAPREDUCE-5583:

bq. As that task completes the ask will go from 0 to 1 since we can now run another task.
In that case oldReqLimit.getNumContainers == 0 and newReqLimit.getNumContainers() == 1, so
they are not the same.
I see. I always forgot our old hacking that compare() in ResourceRequestComparator is inconsistent
with equals() in ResourceRequest. :(
Latest patch LGTM. Given latest patch is upload almost 1 week ago, kick off Jenkins test again.

+1 pending on Jenkins result.

> Ability to limit running map and reduce tasks
> ---------------------------------------------
>                 Key: MAPREDUCE-5583
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5583
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: mr-am, mrv2
>    Affects Versions: 0.23.9, 2.1.1-beta
>            Reporter: Jason Lowe
>            Assignee: Jason Lowe
>         Attachments: MAPREDUCE-5583-branch2.4.1.patch, MAPREDUCE-5583v1.patch, MAPREDUCE-5583v2.patch,
MAPREDUCE-5583v3.patch, MAPREDUCE-5583v4.patch
> It would be nice if users could specify a limit to the number of map or reduce tasks
that are running simultaneously.  Occasionally users are performing operations in tasks that
can lead to DDoS scenarios if too many tasks run simultaneously (e.g.: accessing a database,
web service, etc.).  Having the ability to throttle the number of tasks simultaneously running
would provide users a way to mitigate issues with too many tasks on a large cluster attempting
to access a serivce at any one time.
> This is similar to the functionality requested by MAPREDUCE-224 and implemented by HADOOP-3412
but was dropped in mrv2.

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