RabbitMQ: messages remain “Unacknowledged”

Question

My Java application sends messages to RabbitMQ exchange, then exchange redirects messages to binded queue. I use Springframework AMQP java plugin with RabbitMQ.

The prob

Answer 1

Just to add my 2 cents for another possible reason for messages staying in an unacknowledged state, even though the consumer makes sure to use the basicAck method-

Sometimes multiple instances of a process with an open RabbitMQ connection stay running, one of which may cause a message to get stuck in an unacknowledged state, preventing another instance of the consumer to ever refetch this message.

You can access the RabbitMQ management console (for a local machine this should be available at localhost:15672), and check whether multiple instances get hold of the channel, or if only a single instance is currently active:

Find the redundant running task (in this case - java) and terminate it. After removing the rogue process, you should see the message jumps to Ready state again.