When I run following test:

for (int i=0; i<2; i++) {
mserver.addNotificationListener(delegateName, dummyListener, null, s1);
mserver.addNotificationListener(delegateName, dummyListener, null, s2);
mserver.addNotificationListener(delegateName, dummyListener, null, s3);

mserver.removeNotificationListener(delegateName, dummyListener);

try {
mserver.removeNotificationListener(delegateName, dummyListener, null, s1);
System.out.println("Failed to remove a listener.");
return false;
} catch (ListenerNotFoundException lne) {
// As expected.
}
}

the first cycle is well passed, but since second cycle, the main thread is blocked for a while when adding the listener second time.

The test is passed, but it takes long time