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From "Wangda Tan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-2456) Possible deadlock in CapacityScheduler when RM is recovering apps
Date Wed, 10 Sep 2014 03:27:29 GMT

    [ https://issues.apache.org/jira/browse/YARN-2456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14127989#comment-14127989

Wangda Tan commented on YARN-2456:

In addition, I suggest to change the {{deadlock}} of the title to be {{livelock}}, because
no thread is locked here, it just a weird state preventing the state to make progress, instead
of lock. See: http://en.wikipedia.org/wiki/Deadlock#Livelock


> Possible deadlock in CapacityScheduler when RM is recovering apps
> -----------------------------------------------------------------
>                 Key: YARN-2456
>                 URL: https://issues.apache.org/jira/browse/YARN-2456
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: resourcemanager
>            Reporter: Jian He
>            Assignee: Jian He
>         Attachments: YARN-2456.1.patch
> Consider this scenario:
> 1. RM is configured with a single queue and only one application can be active at a time.
> 2. Submit App1 which uses up the queue's whole capacity
> 3. Submit App2 which remains pending.
> 4. Restart RM.
> 5. App2 is recovered before App1, so App2 is added to the activeApplications list. Now
App1 remains pending (because of max-active-app limit)
> 6. All containers of App1 are now recovered when NM registers, and use up the whole queue
capacity again.
> 7. Since the queue is full, App2 cannot proceed to allocate AM container.
> 8. In the meanwhile, App1 cannot proceed to become active because of the max-active-app

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