discardOld

For topics, discardOld specifies that, if any of the subscribers have an outstanding number of undelivered messages on the server that are over the message limit, the oldest messages are discarded before they are delivered to the subscriber.

The discardOld setting impacts subscribers individually. For example, you might have three subscribers to a topic, but only one subscriber exceeds the message limit. In this case, only the oldest messages for the one subscriber are discarded, while the other two subscribers continue to receive all of their messages.

When messages for a topic or queue exceed the maxbytes or maxmsgs value, the oldest messages are silently discarded. No error is returned to the producer.