VmComponent

[William Tam]

We might want to add this to VmComponent as a way to clear out the
static Map of BlockingQueues.   Notice that once the vm component has
been stopped, entriies in the queues are deleted.  Starting it again
will start with a clean slate.

    @Override
    protected void doStop() throws Exception {
        super.doStop();
        synchronized (queues) {
            for (BlockingQueue q : queues.values()) {
                q.clear();
            }
            queues.clear();
        }
    }