Why do some openstack services fail to finish tasks showing "message timeout" error in the logs?

Issue

• Various openstack tasks fail with below error message in the logs. The tasks can be anything that uses messaging service like spawning instances in batches, creating networks, volumes, etc. The failure is usually random, eg. two or three instances fail to spawn if we spawn a batch of 10 instances.

MessagingTimeout: Timed out waiting for a reply to message ID xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

• Restarting rabbitmq-server service may solve this problem temporarily, but will eventually exhibit after some time.