There's a good chance that this could be related to: http://jira.jboss.org/jira/browse/JBMESSAGING-1245 Messages are getting 'stuck' in the database and I have to restart a single app server before these messages are delivered However, this problem only seems to happen very sporadically (around every 10-14 days) on our production environment and hence im hesitent of changing the prefetchSize before asking the forum. We are using Jboss AS 4.2.2.GA and JBM 1.4.0.SP3 backed by a mysql 5 database and JRE 6 on a debian OS. The queues are clustered over 3 servers. We are using the MessageConsumer.receive(1000) method to receive messages that runs every 1-5 seconds depending on the queue. I know this is happening as some newer messages are being delivered correctly. The queues all have the following properties set: Clustered=true and MaxDeliveryAttempts=1 Below are the queue message counts - 99% of these are messages that are stuck on the queues. server 1: queueA=357,queueB=0,queueC=51,queueD=8 server 2: queueA=353,queueB=3,queueC=941,queueD=1 server 3: queueA=9,queueC=5,queueC=37,queueD=2 After restarting server 1 using the jboss shutdown.sh script all messages on servers2 and 3 were sent and then after starting server 1 all messages on its queues were then delivered. I would doubt our code doing the batching effect if it wasn't for this re-starting behaviour. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4135251#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...