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https://issues.apache.org/jira/browse/YARN-4390?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15027020#comment-15027020
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Eric Payne commented on YARN-4390:
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[~bikassaha], thank you for your comments.
{quote}
However, if YARN ends up preempting 8x1GB containers on different nodes then 
the under-allocated AM will not get its resources and may result in further 
avoidable preemptions. 
{quote}
This is the scenario I was documenting in the description.

> Consider container request size during CS preemption
> ----------------------------------------------------
>
>                 Key: YARN-4390
>                 URL: https://issues.apache.org/jira/browse/YARN-4390
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: capacity scheduler
>    Affects Versions: 3.0.0, 2.8.0, 2.7.3
>            Reporter: Eric Payne
>            Assignee: Eric Payne
>
> There are multiple reasons why preemption could unnecessarily preempt 
> containers. One is that an app could be requesting a large container (say 
> 8-GB), and the preemption monitor could conceivably preempt multiple 
> containers (say 8, 1-GB containers) in order to fill the large container 
> request. These smaller containers would then be rejected by the requesting AM 
> and potentially given right back to the preempted app.



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