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https://issues.apache.org/jira/browse/YARN-4606?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16345536#comment-16345536
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Manikandan R commented on YARN-4606:
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[~leftnoteasy] Based on my understanding, as of now
{{ActiveUsersManager#getNumActiveUsers}} has been used only in
{{LeafQueue#getUserAMResourceLimitPerPartition}} to compute the userAMLimit.
Given this, ensuring active users count increments only after app activation is
sufficient to fix this JIRA? Something like,
1. Introduce a new method {{activeApplication()}} in {{AppSchedulingInfo}} to
set new private boolean variable "isActivated" to true.
2. Call #1 from {{LeafQueue#activateApplications}} after
{{application.updateAMContainerDiagnostics(AMState.ACTIVATED, null);}} similar
to changes in earlier POC patch.
3. Ensure {{abstractUsersManager.activateApplication(user, applicationId);}}
in {{AppSchedulingInfo#updatePendingResources}} executes only when isActivate
is true.
Please share your views.
> CapacityScheduler: applications could get starved because computation of
> #activeUsers considers pending apps
> -------------------------------------------------------------------------------------------------------------
>
> Key: YARN-4606
> URL: https://issues.apache.org/jira/browse/YARN-4606
> Project: Hadoop YARN
> Issue Type: Bug
> Components: capacity scheduler, capacityscheduler
> Affects Versions: 2.8.0, 2.7.1
> Reporter: Karam Singh
> Assignee: Wangda Tan
> Priority: Critical
> Attachments: YARN-4606.1.poc.patch
>
>
> Currently, if all applications belong to same user in LeafQueue are pending
> (caused by max-am-percent, etc.), ActiveUsersManager still considers the user
> is an active user. This could lead to starvation of active applications, for
> example:
> - App1(belongs to user1)/app2(belongs to user2) are active, app3(belongs to
> user3)/app4(belongs to user4) are pending
> - ActiveUsersManager returns #active-users=4
> - However, there're only two users (user1/user2) are able to allocate new
> resources. So computed user-limit-resource could be lower than expected.
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