Slow consumers can be identified for both queues and topics. But whereas one of the primary responses (terminate the subscription and force the consumer to re-subscribe) will protect the broker in the case of a non-durable topic subscription (because the broker no longer needs to keep those unconsumed messages for that consumer, since there is no longer a subscription for the consumer), forcing a disconnect of a slow consumer for a queue or a durable topic subscription typically just make the consumer even slower by interfering with its ability to consume the messages. So although it's definitely possible to identify slow consumers for both queues and topics, people tend to focus more on topics than on queues.
The pending message limit strategy will discard older unconsumed messages for a particular subscription, to keep the total number of unconsumed messages below a particular maximum value. There are two flavors: ConstantPendingMessageLimitStrategy, which has a fixed limit that's applied to all consumers, and PrefetchRatePendingMessageLimitStrategy, which specifies the value as a multiplier on each consumer's prefetch queue size (and therefore allows the possibility of differing limits for different consumers). Tim On Thu, Nov 21, 2019 at 2:50 AM Jérôme Barotin <j...@s4e.fr> wrote: > Hi, > > I just went to read the page in documentation about slow consumer > handling : http://activemq.apache.org/slow-consumer-handling.html and I > have two questions : > > * Is "slow consumer" feature exists about queue ? in the doc there's > only topic mentioned. > * what is the default pending message limit strategy ? > > Best, > > -- > > *Jérome* >
