[jira] [Commented] (YARN-3453) Fair Scheduler : Parts of preemption logic uses DefaultResourceCalculator even in DRF mode causing thrashing

["Arun Suresh (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/YARN-3453?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14615236#comment-14615236 ] 

Arun Suresh commented on YARN-3453:
-----------------------------------

Apologize for the delay.
Thanks for the review [~ashwinshankar77].

bq. Why are we not using componentwisemin here ?
Yup.. this can be changed to componentwisemin.

bq. FairScheduler.preemptResources() uses DefaultResourceCalculator and hence would look at only memory.
Agree.. And as you mentioned, think we will have to fix YARN-2154 too.

> Fair Scheduler : Parts of preemption logic uses DefaultResourceCalculator even in DRF mode causing thrashing
> ------------------------------------------------------------------------------------------------------------
>
>                 Key: YARN-3453
>                 URL: https://issues.apache.org/jira/browse/YARN-3453
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: fairscheduler
>    Affects Versions: 2.6.0
>            Reporter: Ashwin Shankar
>            Assignee: Arun Suresh
>         Attachments: YARN-3453.1.patch, YARN-3453.2.patch
>
>
> There are two places in preemption code flow where DefaultResourceCalculator is used, even in DRF mode.
> Which basically results in more resources getting preempted than needed, and those extra preempted containers aren’t even getting to the “starved” queue since scheduling logic is based on DRF's Calculator.
> Following are the two places :
> 1. {code:title=FSLeafQueue.java|borderStyle=solid}
> private boolean isStarved(Resource share)
> {code}
> A queue shouldn’t be marked as “starved” if the dominant resource usage
> is >=  fair/minshare.
> 2. {code:title=FairScheduler.java|borderStyle=solid}
> protected Resource resToPreempt(FSLeafQueue sched, long curTime)
> {code}
> --------------------------------------------------------------
> One more thing that I believe needs to change in DRF mode is : during a preemption round,if preempting a few containers results in satisfying needs of a resource type, then we should exit that preemption round, since the containers that we just preempted should bring the dominant resource usage to min/fair share.



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