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https://issues.apache.org/jira/browse/YARN-4280?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kuhu Shukla updated YARN-4280:
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Attachment: YARN-4280.007.patch
Thank you so much [~leftnoteasy] for the detailed review and offline
explanation. I have rectified the patch for Point#1, which subtracts
max(child.headroom,none()) from parentLimits if QUEUE_SKIPPED is received.
For point 2. I think it would still work as follows:
Given the queue configuration in the above example with all queues
max-capacity=100%, when the first QUEUE_SKIPPED is received from a1 to a, the
parent limit for a will be set to (50-2) since childlimits.getHeadroom will be
2. Now when {{getResourceLimitsOfChild}} is called with parentLimits=48, the
value of {{parentMaxAvailableResource}} will be zero and the childLimit for a2
will be (0+24) which would inhibit a2 to go through with assignment request of
1.
Let me know your thoughts/concerns regarding this. Thanks a lot!
> CapacityScheduler reservations may not prevent indefinite postponement on a
> busy cluster
> ----------------------------------------------------------------------------------------
>
> Key: YARN-4280
> URL: https://issues.apache.org/jira/browse/YARN-4280
> Project: Hadoop YARN
> Issue Type: Bug
> Components: capacity scheduler
> Affects Versions: 2.6.1, 2.8.0, 2.7.1
> Reporter: Kuhu Shukla
> Assignee: Kuhu Shukla
> Attachments: YARN-4280.001.patch, YARN-4280.002.patch,
> YARN-4280.003.patch, YARN-4280.004.patch, YARN-4280.005.patch,
> YARN-4280.006.patch, YARN-4280.007.patch
>
>
> Consider the following scenario:
> There are 2 queues A(25% of the total capacity) and B(75%), both can run at
> total cluster capacity. There are 2 applications, appX that runs on Queue A,
> always asking for 1G containers(non-AM) and appY runs on Queue B asking for 2
> GB containers.
> The user limit is high enough for the application to reach 100% of the
> cluster resource.
> appX is running at total cluster capacity, full with 1G containers releasing
> only one container at a time. appY comes in with a request of 2GB container
> but only 1 GB is free. Ideally, since appY is in the underserved queue, it
> has higher priority and should reserve for its 2 GB request. Since this
> request puts the alloc+reserve above total capacity of the cluster,
> reservation is not made. appX comes in with a 1GB request and since 1GB is
> still available, the request is allocated.
> This can continue indefinitely causing priority inversion.
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