[jira] [Created] (YARN-1909) FairScheduler isStartvedForFairShare does not work when fairShare == 1

["Anubhav Dhoot (JIRA)" <ji...@apache.org>]

Anubhav Dhoot created YARN-1909:
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             Summary: FairScheduler isStartvedForFairShare does not work when fairShare == 1
                 Key: YARN-1909
                 URL: https://issues.apache.org/jira/browse/YARN-1909
             Project: Hadoop YARN
          Issue Type: Bug
            Reporter: Anubhav Dhoot
            Assignee: Anubhav Dhoot


If the fair share returned by the scheduler getFairShare() == 1 the pool will never be marked as being starved because of the following calculation:
boolean isStarvedForFairShare(PoolSchedulable sched) { int desiredFairShare = (int) Math.floor(Math.min( sched.getFairShare() / 2, sched.getDemand())); return (sched.getRunningTasks() < desiredFairShare); }
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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