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From "Nathan Roberts (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-3298) User-limit should be enforced in CapacityScheduler
Date Mon, 09 Mar 2015 14:50:38 GMT

    [ https://issues.apache.org/jira/browse/YARN-3298?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14353053#comment-14353053

Nathan Roberts commented on YARN-3298:

Thanks [~leftnoteasy] for the additional detail. Maybe I should just wait for the patch, but
here's the case I'm worried about.

queue.used is just under queue.capacity, so current-capacity = queue.capacity.
two users in the queue, both have same used resources

user-limit will be slightly less than (queue-capacity/2). (so user-limit can be extremely
close to user.usage)

user.usage + required might now be slightly greater than user-limit. If that happens, it seems
like we'll be unable to cross the capacity threshold. Once above capacity, I think it will
work, but crossing that threshold might be hard.

Seems like current-capacity should be calculated as:
current-capacity = max(queue.used,queue.capacity)+now-required;

> 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
> (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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