Knut Saua Mathiesen created AMQ-7362:
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Summary: Concurrency bug in closing of VMTransportServer?
Key: AMQ-7362
URL: https://issues.apache.org/jira/browse/AMQ-7362
Project: ActiveMQ
Issue Type: Bug
Reporter: Knut Saua Mathiesen
I'm trying to hunt down why my application, when using a vm broker, will not
shutdown gracefully.
Though I have not found the problem (yet) I might have found a concurrency bug
in the VMTransportServer code:
{code:java}
VMTransport client = new VMTransport(location) {
public void stop() throws Exception {
if (!disposed.get()) {
super.stop();
if (connectionCount.decrementAndGet() == 0 && disposeOnDisconnect) {
VMTransportServer.this.stop();
}
}
};
};{code}
My debugger tells me that I've managed to get connectionCount less than 0 which
does not make any sense.
>From what I can see
{code}disposed.get(){code} returns false it will call super.stop() which does a
compareAndSet on dispose
{code}
@Override
public void stop() throws Exception {
// Only need to do this once, all future oneway calls will now
// fail as will any asnyc jobs in the task runner.
if (disposed.compareAndSet(false, true)) {
{code}
One could easily imagine that two threads both come to the conclusion that
disposed.get() returns false, while only one of the will be allowed into the
body of VMTransport#stop().
The second thread will still decrement the connectionCount which as far as I
can see is wrong.
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