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https://issues.apache.org/jira/browse/YARN-3405?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14385124#comment-14385124
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Peng Zhang commented on YARN-3405:
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[~kasha]
What the real problem I met in our cluster is livelock. After checking code, I
think it has some other bad cases like we talked above.
I list them together because I think they has the same basic problem:
"calculation of preemption request and preemption of container are separated as
two phases", lot of necessary info is lost between these two phases.
For less confusion, I created YARN-3414 to discuss livelock problem.
And I'll update this description to show non-livelock case that I think.
> FairScheduler's preemption cannot happen between sibling in some case
> ---------------------------------------------------------------------
>
> Key: YARN-3405
> URL: https://issues.apache.org/jira/browse/YARN-3405
> Project: Hadoop YARN
> Issue Type: Bug
> Components: fairscheduler
> Affects Versions: 2.7.0
> Reporter: Peng Zhang
> Priority: Critical
>
> Queue hierarchy described as below:
> {noformat}
> root
> |
> queue-1
> / \
> queue-1-1 queue-1-2
> {noformat}
> 1. When queue-1-1 is active and it has been assigned with all resources.
> 2. When queue-1-2 is active, and it cause some new preemption request.
> 3. But when do preemption, it now starts from root, and found queue-1 is not
> over fairshare, so no recursion preemption to queue-1-1.
> 4. Finally queue-1-2 will be waiting for resource release form queue-1-1
> itself.
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