[jira] Resolved: (AMQ-1856) Deadlock in AMQMessageStore when using transactions

["Rob Davies (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/activemq/browse/AMQ-1856?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rob Davies resolved AMQ-1856.
-----------------------------

    Fix Version/s: 5.2.0
       Resolution: Fixed

Fixed by SVN revision 676636

> Deadlock in AMQMessageStore when using transactions
> ---------------------------------------------------
>
>                 Key: AMQ-1856
>                 URL: https://issues.apache.org/activemq/browse/AMQ-1856
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker
>    Affects Versions: 5.1.0
>         Environment: Red Hat Enterprise Linux ES release 4 (Nahant Update 3)
> jdk1.6.0_07
>            Reporter: J Moran
>            Assignee: Rob Davies
>            Priority: Blocker
>             Fix For: 5.2.0
>
>         Attachments: AMQ-1856.patch, thread_dump.txt
>
>
> I am using ActiveMQ 5.1.0 with the AMQMessageStore (in the default configuration except data directory location) and sending/receiving transactionally using the VMTransport. This produced the deadlock shown in the attached (partial) thread dump, generated by jstack -l. 
> In a nutshell, the VMTransport thread is holding the AMQMessageStore.lock=KahaReferenceStore.lock, acquired at AMQMessageStore.java:231, while awaiting a countDown on AMQMessageStore.flushLatch. The ActiveMQ Task (which is the AMQMessageStore.asyncWriteTask) should do the countDown on the flushLatch but is waiting on acquiring the KahaReferenceStore.lock first. Hence deadlock.
> Note that the condition messageAcks.size() > this.peristenceAdapter.getMaxCheckpointMessageAddSize() must be true for the deadlock to occur -- this triggers the flush. 
> Since the transport is one of the deadlocked threads, all access via the transport stops, making the broker unusable and making this issue a blocker for me. A comment (workaround?) as soon as possible would be much appreciated.

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