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https://issues.apache.org/jira/browse/YARN-4606?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15108267#comment-15108267
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Naganarasimha G R commented on YARN-4606:
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Hi [~wangda],
Thanks for sharing the proposal, Just to clarify whether my understanding is 
correct : 
* While calculating user limit for assigning containers to a app we take the 
#activeusers = #users who have apps in activated stage and has outstanding 
requests. 
* And while calculating userAMlimit for activating a app we take #activeusers = 
#unique users who are having apps in the pending order policy?
 

> 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
>
> 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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