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https://issues.apache.org/jira/browse/YARN-596?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13951040#comment-13951040
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Sandy Ryza commented on YARN-596:
---------------------------------
Cloning the full queue/app tree makes preemption O(apps) vs. O(log(apps)),
which seems expensive to do every time we want to preempt.
Could we possibly add a field to Schedulable called something like
preemptedResources that gets subtracted when calculating getResourceUsage, and
cleared out at the end of preemptResources?
Also, minor nit: better to use "sched" than "sche" for consistency with other
places in the code.
> In fair scheduler, intra-application container priorities affect
> inter-application preemption decisions
> -------------------------------------------------------------------------------------------------------
>
> Key: YARN-596
> URL: https://issues.apache.org/jira/browse/YARN-596
> Project: Hadoop YARN
> Issue Type: Bug
> Components: scheduler
> Affects Versions: 2.0.3-alpha
> Reporter: Sandy Ryza
> Assignee: Sandy Ryza
> Attachments: YARN-596.patch, YARN-596.patch, YARN-596.patch,
> YARN-596.patch
>
>
> In the fair scheduler, containers are chosen for preemption in the following
> way:
> All containers for all apps that are in queues that are over their fair share
> are put in a list.
> The list is sorted in order of the priority that the container was requested
> in.
> This means that an application can shield itself from preemption by
> requesting it's containers at higher priorities, which doesn't really make
> sense.
> Also, an application that is not over its fair share, but that is in a queue
> that is over it's fair share is just as likely to have containers preempted
> as an application that is over its fair share.
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