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Posted to dev@qpid.apache.org by "Keith Wall (Updated) (JIRA)" <ji...@apache.org> on 2012/01/13 15:43:40 UTC
[jira] [Updated] (QPID-3697) SortedQueue synchronization causes
deadlock
[ https://issues.apache.org/jira/browse/QPID-3697?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Keith Wall updated QPID-3697:
-----------------------------
Status: Ready To Review (was: In Progress)
> SortedQueue synchronization causes deadlock
> -------------------------------------------
>
> Key: QPID-3697
> URL: https://issues.apache.org/jira/browse/QPID-3697
> Project: Qpid
> Issue Type: Bug
> Components: Java Broker
> Affects Versions: 0.5, 0.15
> Environment: All
> Reporter: Philip Harvey
> Assignee: Keith Wall
>
> We've seen a broker become unresponsive several times in Production.
> Analysis of a thread dump showed a deadlock between two threads, namely:
> - a thread that is calling SortedQueue.enqueue, which has already locked the SortedQueue and is trying to lock the Subscription's sendLock
> - a thread that is closing a session by calling AMQChannel.unsubscribeAllConsumers, which has already locked the Subscription's sendLock and is trying to lock the SortedQueue.
> The suggested fix is for SortedQueue.enqueue to not be synchronized, thereby removing the possibility of this deadlock occuring. SortedQueue.enqueue should instead lock on a private Object.
> Note that SortedQueue is the only queue that is susceptible to this deadlock because it is the only one that has a synchronized enqueue method.
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