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https://issues.apache.org/jira/browse/YARN-10559?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17269420#comment-17269420
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Eric Payne commented on YARN-10559:
-----------------------------------
Thanks [~ananyo_rao] for bringing up this issue and for providing a patch.
Sorry for my delay in responding.
I think the overall requirements seem reasonable. Preemption is supposed to
mimic what the capacity scheduler would do when a queue has FairOrderingPolicy
set if all jobs were launched simultaneously. So preempting from a user's first
app to give to the same user's second app makes sense.
The only caveat I would add is that (as is the case with all preempted
containers) just because the preemption monitor decides to preempt a container
because of a particular request, that doesn't mean that the capacity scheduler
will then assign the container as expected. The states of the queue and cluster
are constantly in flux and so a container preempted for one app could easily go
to a different app in the same queue or a different queue.
I will try to look at the changes next week.
> Fair sharing intra-queue preemption support in Capacity Scheduler
> -----------------------------------------------------------------
>
> Key: YARN-10559
> URL: https://issues.apache.org/jira/browse/YARN-10559
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: capacityscheduler
> Affects Versions: 3.1.4
> Reporter: VADAGA ANANYO RAO
> Assignee: VADAGA ANANYO RAO
> Priority: Major
> Attachments: FairOP_preemption-design_doc_v1.pdf,
> FairOP_preemption-design_doc_v2.pdf, YARN-10559.0001.patch,
> YARN-10559.0002.patch, YARN-10559.0003.patch, YARN-10559.0004.patch,
> YARN-10559.0005.patch, YARN-10559.0006.patch, YARN-10559.0007.patch,
> YARN-10559.0008.patch
>
> Original Estimate: 168h
> Remaining Estimate: 168h
>
> Usecase:
> Due to the way Capacity Scheduler preemption works, If a single user submits
> a large application to a queue (using 100% of resources), that job will not
> be preempted by future applications from the same user within the same queue.
> This implies that the later applications will be forced to wait for
> completion of the long running application. This prevents multiple long
> running, large, applications from running concurrently.
> Support fair sharing among apps while preempting applications from same queue.
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