Note that if processing a particular message exceeds ack wait, the following behavior can be observed with queue subscriptions: 1. Subscriber A receives the message. 2. Subscriber A exceeds ack wait time and Subscriber B receives the message. 3. Subscriber B exceeds ack wait time and Subscriber C receives the message. 6. Subscriber A finishes processing and acknowledges the message. 7. Re-delivery of the message ceases.How often the message is re-delivered depends on processing time for the message and available subscriber.