[jboss-user] [Clustering/JBoss] - Re: Session Replication - Concurrency Problems?

davewebb do-not-reply at jboss.com
Wed May 9 16:59:24 EDT 2007

Mr Stansberry,

We're using sticky sessions, we understand how to configure them and as far as I know they are working correctly, but we are still seeing the "Possible concurrency problem" message."

To elaborate a little on our configuration, we use jBoss4.0.5GA with Apache 2.2.4 on the front end using mod_proxy_ajp for load balancing.

There are actually 2 issues we are seeing:

1) The "Possible Concurrency Problem" message.  We are using REPL_ASYNC and REPEATABLE_READ in the tc5 cluster setup.  I should note that we used the same setup in our last environment which was 4.0.2 and everything worked fine.

2) Although we have mod_proxy_ajp setup to use sticky sessions, it doesnt appear to be doing that, hence the discovery of #1 above b/c we get NPEs accessing session attributes as mod_proxy distributes requests across multiple JBoss instances and the session attributes arent being replicated properly.

I think a solution to either of these 2 problems helps out everyone, although I recognize #2 is probably not within the scope of this thread.  I think regardless of StickySession (which I fully understand), there is an issue with Session replication.

Hope this helps and we appreciate your time and attention to this forum. Thank you.

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