[jboss-jira] [JBoss JIRA] Closed: (JBAOP-501) Deadlock involving exclusively AspectManager and ClassLoader locks

[Flavia Rainone (JIRA)]

     [ http://jira.jboss.com/jira/browse/JBAOP-501?page=all ]

Flavia Rainone closed JBAOP-501.
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> Deadlock involving exclusively AspectManager and ClassLoader locks
> ------------------------------------------------------------------
>
>                 Key: JBAOP-501
>                 URL: http://jira.jboss.com/jira/browse/JBAOP-501
>             Project: JBoss AOP
>          Issue Type: Sub-task
>      Security Level: Public(Everyone can see) 
>    Affects Versions: 2.0.0.CR2
>            Reporter: Flavia Rainone
>         Assigned To: Flavia Rainone
>             Fix For: 2.0.0.CR8
>
>         Attachments: aop_deadlock.txt
>
>
> This deadlock involves only the AspectManager and the class loader locks. The scenario, result of a rebuildingchain test execution, follows:
> -Thread 0 (org.jboss.test.aop.rebuldingchain.SyncThread)
>  When this thread calls the joinpoint SyncThread.checkStatus, its wrapper is executed. This wrapper needs to generate
>  the Joinpoint class to perform the interception and, for that, it has to acquire the read lock for InterceptorChain.  This thread 
> starts waiting for Thread1 to release the interceptor chain write lock.
> - Thread 1 (org.jboss.test.aop.rebuildingchain.RebuildThread)
>   This thread adds a binding to AspectManager. As part of the addBinding method execution, the AspectManager lock is acquired. 
> As soon as the binding is addded to the bindings collection, the affected advisors have to rebuild their interceptor chains. SyncThread 
> advisor is the affected advisor in this scenario and, to rebuild chains, it needs the write lock for the SyncThread.checkStatus inteceptor 
> chain. This lock is acquired and the rebuild chain algorithm starts being executed. During the finalization of fhe chains, interceptors are 
> created. For that, the interceptor class needs to be loaded, so this thread starts waiting for the class loader lock, held by Main Thread.
> - Main Thread
> Test tries to finish execution (without joining the other threads) and, for that, it starts loading a class, acquiring the class loader lock. The 
> class loading proccess triggers AOPTransformer, that tries to transform the loaded class. For that, the AspectManager lock, held by Thread1, 
> is required, so thist thread starts waiting for that lock.
> Notice that the deadlock involves only Thread1 and MainThread (Thread0 is present only for completion).

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