[jira] [Commented] (MESOS-429) Hadoop MesosScheduler has a deadlock.

["Benjamin Mahler (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MESOS-429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13625915#comment-13625915 ] 

Benjamin Mahler commented on MESOS-429:
---------------------------------------

https://reviews.apache.org/r/10352/
                
> Hadoop MesosScheduler has a deadlock.
> -------------------------------------
>
>                 Key: MESOS-429
>                 URL: https://issues.apache.org/jira/browse/MESOS-429
>             Project: Mesos
>          Issue Type: Bug
>            Reporter: Benjamin Mahler
>            Assignee: Benjamin Mahler
>            Priority: Blocker
>
> This was found with the help of Brenden Matthews.
> JobTracker.heartbeat (synchronized) calls MesosScheduler.assignTasks (synchronized)
> MesosScheduler.resourceOffers (synchronized) calls into JobTracker.getJobStatus (synchronized).
> Thread 24558: (state = BLOCKED)
>  - org.apache.hadoop.mapred.JobTracker.getJobStatus(java.util.Collection, boolean) @bci=0, line=4592 (Interpreted frame)
>  - org.apache.hadoop.mapred.JobTracker.jobsToComplete() @bci=11, line=4157 (Interpreted frame)
>  - org.apache.hadoop.mapred.MesosScheduler.resourceOffers(org.apache.mesos.SchedulerDriver, java.util.List) @bci=9, line=273 (Compiled frame)
> Thread 24575: (state = BLOCKED)
>  - org.apache.hadoop.mapred.MesosScheduler.assignTasks(org.apache.hadoop.mapreduce.server.jobtracker.TaskTracker) @bci=25, line=219 (Compiled frame)
>  - org.apache.hadoop.mapred.JobTracker.heartbeat(org.apache.hadoop.mapred.TaskTrackerStatus, boolean, boolean, boolean, short) @bci=507, line=2951 (Compiled frame)
> The simplest fix for now would be to unsynchronize the Scheduler interface implementations. As a result, when we have to modify the state of MesosScheduler inside those methods, we need to do so in a synchronized block. So long as we don't invoke the JobTracker methods from these synchronized blocks, we won't have a deadlock. We can clean this up later, if a cleaner abstraction is needed.

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