I recently upgraded a server from ActiveMQ from 5.8 to the latest (5.11.1). Since then, I've noticed somewhat sporadically that messages will build up on a particular queue and not be taken off.
Our architecture has one producer, one consumer. I can see that the consumer is still connected but messages are piling up from the producer. My solution has been to delete the queue via the web console. After which, I immediately see the consumer reconnect and messages begin being processed again.
If it's relevant, in this case the producer is running NMS on .NET and the consumer is running JMS on Java 1.7.
When the consumer is connected to the queue, please check the number of uncommitted messages in the queue from the web console. If it is more than zero and does not change for a long time, it means your consumer is having some problem in reading the input message.
If the above case is true, it could be because the producer is sending files that is not jms complaint.