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https://issues.apache.org/jira/browse/YARN-3945?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15149365#comment-15149365
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Wangda Tan commented on YARN-3945:
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[~Naganarasimha],
bq. so based on this there will be no elasticity even though the resources are
free in some other queue, is this expected ?
I think so
bq. Are we trying to avoid elasticity because we try to avoid preempting AM's
even when preemption is enabled?
That's the one purpose, the other purpose is, when preemption is disabled, we
will not suffer with too many AMs launched with queue's available resource
increases and then come back.
To make move this task forward, I would suggest:
# Resolve bug of maxApplicationsPerUser should be capped by
maxApplicationsPerQueue
# Computation of user AM limit should be symmetric to computation of
user-limit, and user AM limit should be capped by queue's AM limit
# Avoid flexibility of computing queue and user's AM-limit (do not consider
queue max cap). This needs more discussion.
My understanding is, #1 and #2 are scope of this JIRA, #3 could be done
separately.
Agree?
> maxApplicationsPerUser is wrongly calculated
> --------------------------------------------
>
> Key: YARN-3945
> URL: https://issues.apache.org/jira/browse/YARN-3945
> Project: Hadoop YARN
> Issue Type: Bug
> Components: capacityscheduler
> Affects Versions: 2.7.1
> Reporter: Naganarasimha G R
> Assignee: Naganarasimha G R
> Attachments: YARN-3945.20150728-1.patch, YARN-3945.20150729-1.patch,
> YARN-3945.V1.003.patch
>
>
> maxApplicationsPerUser is currently calculated based on the formula
> {{maxApplicationsPerUser = (int)(maxApplications * (userLimit / 100.0f) *
> userLimitFactor)}} but description of userlimit is
> {quote}
> Each queue enforces a limit on the percentage of resources allocated to a
> user at any given time, if there is demand for resources. The user limit can
> vary between a minimum and maximum value.{color:red} The the former (the
> minimum value) is set to this property value {color} and the latter (the
> maximum value) depends on the number of users who have submitted
> applications. For e.g., suppose the value of this property is 25. If two
> users have submitted applications to a queue, no single user can use more
> than 50% of the queue resources. If a third user submits an application, no
> single user can use more than 33% of the queue resources. With 4 or more
> users, no user can use more than 25% of the queues resources. A value of 100
> implies no user limits are imposed. The default is 100. Value is specified as
> a integer.
> {quote}
> configuration related to minimum limit should not be made used in a formula
> to calculate max applications for a user
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