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

Derek Lewis (JIRA) jira-events at jboss.com
Mon Jan 15 14:38:55 EST 2007


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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