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https://issues.apache.org/jira/browse/YARN-7149?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16166702#comment-16166702
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Wangda Tan commented on YARN-7149:
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[~eepayne],
Thanks for updating the patch, I like the approach which improves headroom
calculation and changes to the code are minimum.
I also checked changes to unit tests, behavior changes looks good to me as
well. So I +1 to the attached patch.
Do you think does it make sense to merge the
https://issues.apache.org/jira/secure/attachment/12885847/YARN-7149.demo.unit-test.patch
to your patch? Which we can prevent issues described by Jason in previous
comments:
bq. It looks like it will be a significant performance hit to do so since we
will keep hitting the limit on each node heartbeat, cutting short the number of
containers we would normally assign per heartbeat.
> Cross-queue preemption sometimes starves an underserved queue
> -------------------------------------------------------------
>
> Key: YARN-7149
> URL: https://issues.apache.org/jira/browse/YARN-7149
> Project: Hadoop YARN
> Issue Type: Bug
> Components: capacity scheduler
> Affects Versions: 2.9.0, 3.0.0-alpha3
> Reporter: Eric Payne
> Assignee: Eric Payne
> Attachments: YARN-7149.001.patch, YARN-7149.demo.unit-test.patch
>
>
> In branch 2 and trunk, I am consistently seeing some use cases where
> cross-queue preemption does not happen when it should. I do not see this in
> branch-2.8.
> Use Case:
> | | *Size* | *Minimum Container Size* |
> |MyCluster | 20 GB | 0.5 GB |
> | *Queue Name* | *Capacity* | *Absolute Capacity* | *Minimum User Limit
> Percent (MULP)* | *User Limit Factor (ULF)* |
> |Q1 | 50% = 10 GB | 100% = 20 GB | 10% = 1 GB | 2.0 |
> |Q2 | 50% = 10 GB | 100% = 20 GB | 10% = 1 GB | 2.0 |
> - {{User1}} launches {{App1}} in {{Q1}} and consumes all resources (20 GB)
> - {{User2}} launches {{App2}} in {{Q2}} and requests 10 GB
> - _Note: containers are 0.5 GB._
> - Preemption monitor kills 2 containers (equals 1 GB) from {{App1}} in {{Q1}}.
> - Capacity Scheduler assigns 2 containers (equals 1 GB) to {{App2}} in {{Q2}}.
> - _No more containers are ever preempted, even though {{Q2}} is far
> underserved_
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