一个ActiveMQ队列中的多个使用者

Question

Say i have several consumers who connect to the same Queue.

My business logic is: take a message from the queue, perform some logical operation and if that operation is successful acknowledge this message (working as client-ack).

My question is, what happens if one of these consumers logic fails and it doesnt return acknowledge on that message.

Is there a risk that this message will be sent to some other consumer while the message is still being processed by a consumer?

Is there some kind of time out after which this message is released by a thread back to the queue?

Answer 1

Messages are dispatched to Consumers in a round robin manner to Queue consumers. If a Consumer fails and the Message it's processing is not acknowledge at the Broker then once the Broker has detected the failure of the consumers connection it will place the message back on the Queue making it available for processing by another connected Consumer.

Its also possible to configure a set maximum number of re-deliveries for a Message such that it will be placed in a Dead Letter Queue after a certain point.