[jira] Resolved: (JCR-2866) Cluster: Node type register/unregister deadlock

["Thomas Mueller (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/JCR-2866?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Thomas Mueller resolved JCR-2866.
---------------------------------

    Resolution: Fixed

This problem should be fixed now.

> Cluster: Node type register/unregister deadlock
> -----------------------------------------------
>
>                 Key: JCR-2866
>                 URL: https://issues.apache.org/jira/browse/JCR-2866
>             Project: Jackrabbit Content Repository
>          Issue Type: Bug
>          Components: clustering
>            Reporter: Thomas Mueller
>            Assignee: Thomas Mueller
>             Fix For: 2.2.2
>
>         Attachments: jcr-2866-a.patch
>
>
> A deadlock can occur when two cluster nodes concurrently register or unregister node types.
> Reason: 
> NodeTypeRegistry.registerNodeTypes is synchronized, and calls eventChannel.registered(ntDefs), which calls AbstractJournal.lockAndSync(), which tries to lock AbstractJournal.rwLock.
> On the other hand, AbstractJournal.sync() locks AbstractJournal.rwLock, then calls NodeTypeRecord.process, which calls NodeTypeRegistry.unregisterNodeTypes, which is also synchronized.
> Possible solutions: Either 
> - NodeTypeRegistry doesn't synchronize on the object when calling a eventChannel method,
> - or NodeTypeRegistry locks AbstractJournal.rwLock before synchronizing.
> There might be other solutions.

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