[jboss-jira] [JBoss JIRA] Closed: (JBAS-3992) Race condition in JBossManagedConnectionFactory

[Weston Price (JIRA)]

     [ http://jira.jboss.com/jira/browse/JBAS-3992?page=all ]

Weston Price closed JBAS-3992.
------------------------------

    Resolution: Rejected

This is expected behavior. The pool and the connection will both be flagged as invalid and will not allow client use. It is a tradeoff between allowing this condition to happen and performance. At the very least, the pool/connection will never be able to be used. 

> Race condition in JBossManagedConnectionFactory
> -----------------------------------------------
>
>                 Key: JBAS-3992
>                 URL: http://jira.jboss.com/jira/browse/JBAS-3992
>             Project: JBoss Application Server
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>          Components: JCA service
>    Affects Versions: JBossAS-4.0.4.GA
>         Environment: I'm running JBoss 4.0.4.GA on jaba 1.5.0_07-b03.
> I haven't tried a newer JBoss, however the code I've determined is causing the
> problem looks the same on 5.0.0.Beta1.
>            Reporter: Derek Lewis
>         Assigned To: Weston Price
>
> The problem happens when calling flush() on JBossManagedConnectionPool via the jmx-console.
> If a call to getConnection() is made by the application at the same time, there is a potential for getConnection() to throw a  ResourceException saying "The pool has been shutdown".
> Thread 1: calls flush()
> Thread 2: calls getConnection()
> In Thread 1, in JBossManagedConnectionPool.flush(), after the pools are iterated through and shut down (this is synchronized on subPools).
> Assume that a context switch happens here, and Thread 2 runs now, with Thread 1 paused, before calling subPools.clear().
> When thread 2 gets to where it calls getSubPool(...), this is not synchronized, so subPools.get(key) returns a pool which is not null  though it has been shutdown), and returns it.
> getConnection() is then called on this pool, causing the exception to be thrown.
> Thread 1 then proceeds to clear the pool, so that the shutdown subpools are not returned.  (But it's too late for this one case)

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