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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-5822) FairScheduler isStartvedForFairShare does not work when fairShare == 1
Date Fri, 11 Apr 2014 21:32:15 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-5822?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13967126#comment-13967126
] 

Hadoop QA commented on MAPREDUCE-5822:
--------------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12639870/MAPREDUCE-5822.002.patch
  against trunk revision .

    {color:red}-1 patch{color}.  The patch command could not apply the patch.

Console output: https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/4504//console

This message is automatically generated.

> FairScheduler isStartvedForFairShare does not work when fairShare == 1
> ----------------------------------------------------------------------
>
>                 Key: MAPREDUCE-5822
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5822
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: scheduler
>    Affects Versions: 1.2.1
>            Reporter: Anubhav Dhoot
>            Assignee: Anubhav Dhoot
>         Attachments: MAPREDUCE-5822.001.patch, MAPREDUCE-5822.002.patch
>
>
> If the fair share returned by the scheduler getFairShare() == 1 the pool will never be
marked as being starved because of the following calculation:
> {code}
> boolean isStarvedForFairShare(PoolSchedulable sched) { 
>   int desiredFairShare = (int) Math.floor(Math.min( sched.getFairShare() / 2, sched.getDemand()));

>   return (sched.getRunningTasks() < desiredFairShare); 
> }
> {code}
> getFairShare() returns 1
> Math.min calculation will return 0.5
> Math.Floor() which will cause the desiredFairShare to be set to 0.
> the return value to be 'false' (0 < 0)
> If you have a small job without a minimum set it will not get scheduled if a large job
is hogging the slots.



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