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https://issues.apache.org/jira/browse/YARN-5864?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15674481#comment-15674481
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Wangda Tan commented on YARN-5864:
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Thanks [~curino] for sharing the firmament paper. I just read it, it provided a
lot of insightful ideas. I believe it can work pretty well for a cluster which
have homogeneous workload, but it may not be able to solve the mix workloads
issues, as it stated:
bq. Firmament shows that a single scheduler can attain scalability, but its
MCMF optimization does not trivially admit multiple independent schedulers.
So in my mind, for YARN, we need borg-like architecture to make different kinds
of workload can be scheduled using different pluggable scheduling policies and
scorers. Firmament could be one of these scheduling policies.
I agree your comment about we should make a better semantics of the feature, I
will think it again and keep you posted.
> Capacity Scheduler preemption for fragmented cluster
> -----------------------------------------------------
>
> Key: YARN-5864
> URL: https://issues.apache.org/jira/browse/YARN-5864
> Project: Hadoop YARN
> Issue Type: New Feature
> Reporter: Wangda Tan
> Assignee: Wangda Tan
> Attachments: YARN-5864.poc-0.patch
>
>
> YARN-4390 added preemption for reserved container. However, we found one case
> that large container cannot be allocated even if all queues are under their
> limit.
> For example, we have:
> {code}
> Two queues, a and b, capacity 50:50
> Two nodes: n1 and n2, each of them have 50 resource
> Now queue-a uses 10 on n1 and 10 on n2
> queue-b asks for one single container with resource=45.
> {code}
> The container could be reserved on any of the host, but no preemption will
> happen because all queues are under their limits.
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