Durable vs. Nondurable Subscriptions

Subscribers to a topic destination have either durable and nondurable subscriptions. Durable subscriptions provide increased reliability at the cost of slower throughput for the following reasons:

• The Message Queue message broker must persistently store the list of messages assigned to each durable subscription so that should the broker fail, the list is available after recovery.

• Persistent messages for durable subscriptions are stored persistently, so that should a broker fail, the messages can still be delivered after recovery, when the corresponding consumer becomes active. By contrast, persistent messages for nondurable subscriptions are not stored persistently (should a broker fail, the corresponding consumer connection is lost and the message would never be delivered).

We compared performance for durable and non-durable subscribers in two cases: persistent and nonpersistent 10k-sized messages. Both cases use AUTO_ACKNOWLEDGE acknowledgment mode. We found a performance impact only in the case of persistent messages, which slowed messages conveyed to durable subscribers by about 30%.