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Date: Wed, 10 Sep 2014 14:04:31 +0000 (UTC)
From: "Hudson (JIRA)" <jira@apache.org>
To: yarn-issues@hadoop.apache.org
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Subject: [jira] [Commented] (YARN-2526) SLS can deadlock when all the
 threads are taken by AMSimulators
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    [ https://issues.apache.org/jira/browse/YARN-2526?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14128491#comment-14128491 ] 

Hudson commented on YARN-2526:
------------------------------

SUCCESS: Integrated in Hadoop-Hdfs-trunk #1867 (See [https://builds.apache.org/job/Hadoop-Hdfs-trunk/1867/])
YARN-2526. SLS can deadlock when all the threads are taken by AMSimulators. (Wei Yan via kasha) (kasha: rev 28d99db99236ff2a6e4a605802820e2b512225f9)
* hadoop-yarn-project/CHANGES.txt
* hadoop-tools/hadoop-sls/src/main/java/org/apache/hadoop/yarn/sls/appmaster/MRAMSimulator.java


> SLS can deadlock when all the threads are taken by AMSimulators
> ---------------------------------------------------------------
>
>                 Key: YARN-2526
>                 URL: https://issues.apache.org/jira/browse/YARN-2526
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: scheduler-load-simulator
>    Affects Versions: 2.5.1
>            Reporter: Wei Yan
>            Assignee: Wei Yan
>            Priority: Critical
>             Fix For: 2.6.0
>
>         Attachments: YARN-2526-1.patch
>
>
> The simulation may enter deadlock if all application simulators hold all threads provided by the thread pool, and all wait for AM container allocation. In that case, all AM simulators wait for NM simulators to do heartbeat to allocate resource, and all NM simulators wait for AM simulators to release some threads. The simulator is deadlocked.
> To solve this deadlock, need to remove the while() loop in the MRAMSimulator.
> {code}
>     // waiting until the AM container is allocated
>     while (true) {
>       if (response != null && ! response.getAllocatedContainers().isEmpty()) {
>         // get AM container
>         .....
>         break;
>       }
>       // this sleep time is different from HeartBeat
>       Thread.sleep(1000);
>       // send out empty request
>       sendContainerRequest();
>       response = responseQueue.take();
>     }
> {code}


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