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https://issues.apache.org/jira/browse/YARN-4280?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kuhu Shukla updated YARN-4280:
------------------------------
    Attachment: YARN-4280.010.patch

Thanks a lot [~jlowe] for the review. I have updated the patch to address the 
comments. This patch removes the change to ResourceLimits. The if block in 
ParentQueue was incorrect and has been removed now to cover cases where all 
child assignments are NULL_ASSIGNMENT(s) with the first(or any one but the 
last)  assignments being a QUEUE_LIMIT skipped case. Will wait for precommit 
and update other  version patches soon.

> CapacityScheduler reservations may not prevent indefinite postponement on a 
> busy cluster
> ----------------------------------------------------------------------------------------
>
>                 Key: YARN-4280
>                 URL: https://issues.apache.org/jira/browse/YARN-4280
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: capacity scheduler
>    Affects Versions: 2.6.1, 2.8.0, 2.7.1
>            Reporter: Kuhu Shukla
>            Assignee: Kuhu Shukla
>         Attachments: YARN-4280-branch-2.009.patch, 
> YARN-4280-branch-2.8.001.patch, YARN-4280-branch-2.8.002.patch, 
> YARN-4280-branch-2.8.003.patch, YARN-4280.001.patch, YARN-4280.002.patch, 
> YARN-4280.003.patch, YARN-4280.004.patch, YARN-4280.005.patch, 
> YARN-4280.006.patch, YARN-4280.007.patch, YARN-4280.008.patch, 
> YARN-4280.008_.patch, YARN-4280.009.patch, YARN-4280.010.patch
>
>
> Consider the following scenario:
> There are 2 queues A(25% of the total capacity) and B(75%), both can run at 
> total cluster capacity. There are 2 applications, appX that runs on Queue A, 
> always asking for 1G containers(non-AM) and appY runs on Queue B asking for 2 
> GB containers.
> The user limit is high enough for the application to reach 100% of the 
> cluster resource. 
> appX is running at total cluster capacity, full with 1G containers releasing 
> only one container at a time. appY comes in with a request of 2GB container 
> but only 1 GB is free. Ideally, since appY is in the underserved queue, it 
> has higher priority and should reserve for its 2 GB request. Since this 
> request puts the alloc+reserve above total capacity of the cluster, 
> reservation is not made. appX comes in with a 1GB request and since 1GB is 
> still available, the request is allocated. 
> This can continue indefinitely causing priority inversion.



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