Sorry, forgot to add: Running JBoss 3.2.7 on RedHat AS4, dual HT Xeons, 4gig ram, talking to an Oracle db
The logic of lowering the priority of the MDB escapes me. If slogging data between tomcat and the client is not the bottleneck, why shouldn't the priority be given to the MDBs? If your saturating the cpu on the box and this is the cause of the increased request latency, you certainly do need to scale the MDB tier to multiple boxes.
The CPU is not running at even close to 100%. To be honest, I can't figure out exactly where the bottleneck is, I only know that it goes if I turn off the MDB. We are using hibernate to perform lookups and update status as a message travels through the system, could this be causing a bottleneck?
Sure. Profile the database server iteraction.
you should verify your last hypothesis by simply outcommenting all processing code within the MDB and check request latency once again. If it is still high, that it's an indicator for the 'messaging bottelneck'.
Do you use persistent messages ? If so do you have enough connections in your connection pools ?
we turned off a significant amount of db udpating, and we got a 3-4 fold performance increase, so it looks as though this is the problem. We are now going to spend the time tuning our database access some more.
Thanks for helping us identify this as the source of our problem.