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https://issues.apache.org/jira/browse/YARN-8379?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16524583#comment-16524583
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Wangda Tan commented on YARN-8379:
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[~Zian Chen],
Thanks for updating the patch,
Few comments:
1) testPreemptionToBalanceWithCustomTimeout is better to move to a separate
class. (Maybe something like TestCapacitySchedulerQueueBalancePreemption. The
test looks not testing this feature, could u check it? I might misunderstand
what you did here.
2) For interface of {{selectCandidates}}, I think we can avoid passing the
curCandidates, correct? According to semantics of curCandidates, it should be
candidates selected *with in the selector*.
An additional comment is:
- Now all selectors need to update two maps, curCandidates and
selectedCandidates, this causes confusion and developers could forget updating
both of them in some cases. Instead of doing this, I think we should refactor
this part of code to simplify the logic. This can be done in a separated JIRA.
[~Zian Chen], could u create a JIRA for this?
> Add an option to allow Capacity Scheduler preemption to balance satisfied
> queues
> --------------------------------------------------------------------------------
>
> Key: YARN-8379
> URL: https://issues.apache.org/jira/browse/YARN-8379
> Project: Hadoop YARN
> Issue Type: Bug
> Reporter: Wangda Tan
> Assignee: Zian Chen
> Priority: Major
> Attachments: YARN-8379.001.patch, YARN-8379.002.patch,
> YARN-8379.003.patch, YARN-8379.004.patch, YARN-8379.005.patch,
> ericpayne.confs.tgz
>
>
> Existing capacity scheduler only supports preemption for an underutilized
> queue to reach its guaranteed resource. In addition to that, there’s an
> requirement to get better balance between queues when all of them reach
> guaranteed resource but with different fairness resource.
> An example is, 3 queues with capacity, queue_a = 30%, queue_b = 30%, queue_c
> = 40%. At time T. queue_a is using 30%, queue_b is using 70%. Existing
> scheduler preemption won't happen. But this is unfair to queue_a since
> queue_a has the same guaranteed resources.
> Before YARN-5864, capacity scheduler do additional preemption to balance
> queues. We changed the logic since it could preempt too many containers
> between queues when all queues are satisfied.
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