private void sleepDeliveryManager(final CountDownLatch wakeupLatch)
throws IOException {
PubSubServer server = serversList.get(0);
assertNotNull("There should be at least one pubsub server", server);
DeliveryManager dm = server.getDeliveryManager();
assertNotNull("Delivery manager should not be null once server has started", dm);
assertTrue("Delivery manager is wrong type", dm instanceof FIFODeliveryManager);
final FIFODeliveryManager fdm = (FIFODeliveryManager)dm;
Thread sleeper = new Thread() {