[AMQ-1897] Non-transactional and exclusive consumer may receive messages out-of-order.

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 5.1.0
• Fix Version/s: 5.3.0
• Component/s: Broker

Environment

Environment:

• ActiveMQ 5.1.0
• one broker using direct jdbc persistence (mysql)
• transacted producer
• non-transacted consumer!
• 3 consumers but all configured for exclusive consumer
• 1 producer that publishes msgs faster than consumers
• consumer using SESSION.AUTO_ACKNOWLEDGE

• Assignee: Robert Davies
• Reporter: Torsten Mielke
• Created: 19/Aug/08 20:02
• Updated: 13/Sep/09 10:40
• Resolved: 13/Sep/09 10:40

Description

With an env as described above it is possible to violate the exclusive consumer limitation. Initially with all three consumers being started and the producer sending messages, the exclusive consumer feature works fine.
However if you kill and restart each consumer in a row, allowing another consumer to take over the exclusive right, you will eventually reach a state where a message that was already consumed by the previous exclusive consumer gets redelivered to the new exclusive consumer that has taken over the work.
As consumers are non-transactional, they will autocommit every single message received, so each msgs gets deleted from the jdbc db sequentially. Hence if another exclusive consumer takes over it should only process messages >= the message number of the previous exclusive consumer. However this is not the case.

This bug is kind of related to AMQ-1896.