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https://issues.apache.org/jira/browse/YARN-3298?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14353852#comment-14353852
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Wangda Tan commented on YARN-3298:
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[~nroberts],
As you mentioned, it is mostly as same as what we have today, and I think it
cannot solve the jitter problem. What I really want to say is enforce the
limit. To solve "small amount of resource cannot be used in a queue" problem
which you mentioned in
https://issues.apache.org/jira/browse/YARN-3298?focusedCommentId=14353053&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14353053,
setting user-limit a little bit higher should solve the problem also. (like
from 50 to 51).
Sounds like a plan?
> User-limit should be enforced in CapacityScheduler
> --------------------------------------------------
>
> Key: YARN-3298
> URL: https://issues.apache.org/jira/browse/YARN-3298
> Project: Hadoop YARN
> Issue Type: Bug
> Components: capacityscheduler, yarn
> Reporter: Wangda Tan
> Assignee: Wangda Tan
>
> User-limit is not treat as a hard-limit for now, it will not consider
> required-resource (resource of being-allocated resource request). And also,
> when user's used resource equals to user-limit, it will still continue. This
> will generate jitter issues when we have YARN-2069 (preemption policy kills a
> container under an user, and scheduler allocate a container under the same
> user soon after).
> The expected behavior should be as same as queue's capacity:
> Only when user.usage + required <= user-limit (1), queue will continue to
> allocate container.
> (1), user-limit mentioned here is determined by following computing
> {code}
> current-capacity = queue.used + now-required (when queue.used >
> queue.capacity)
> queue.capacity (when queue.used < queue.capacity)
> user-limit = min(max(current-capacity / #active-users, current-capacity *
> user-limit / 100), queue-capacity * user-limit-factor)
> {code}
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