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https://issues.apache.org/jira/browse/YARN-4606?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16463324#comment-16463324
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Wangda Tan commented on YARN-4606:
----------------------------------
Thanks [~maniraj...@gmail.com],
Some questions:
1) Does this patch handles the case that one user has multiple pending apps?
(Since it doesn't store user to apps information).
2)
{code}
abstractUsersManager.decrNumActiveUsersOfPendingApps();
{code}
Should we call this inside
{{SchedulerApplicationAttempt#pullNewlyUpdatedContainers}}?
I think we should remove active user from pending apps once AM container get
allocated.
3)
{code}
Resources.lessThan(rc, cr,
metrics.getUsedAMResources(), metrics.getMaxAMResources())
{code}
Instead of using metrics, it might be better to use
{{SchedulerApplicationAttempt#getAppAttemptResourceUsage}} instead.
> 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: Manikandan R
> Priority: Critical
> Attachments: YARN-4606.001.patch, YARN-4606.1.poc.patch,
> YARN-4606.POC.2.patch, YARN-4606.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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