users@glassfish.java.net

MDB Tuning and Pool Size

From: <glassfish_at_javadesktop.org>
Date: Tue, 26 Aug 2008 06:54:35 PDT

Hello,

I have a question regarding tuning MDBs in glassfish. We have a transaction processing application that consists of a series of MDBs. Messages are read from one queue, run through some business logic, and placed on another queue. From beginning to end, there are about 5 hops (queues).

We are trying to tune the system by adjusting the number of MDB instances for each hop to ensure that there is no buildup on any of the queues. But we are seeing some odd behaviour.

If we flood the system with 1000 messages and set a max-pool-size of 200 for a particular MDB, glassfish never seems to create enough instances. The incoming queue the MDB is listening to has 1000 messages but glassfish never maxes out to 200 instanes. We see numbers closer to the steady-pool-size of 100.

I would think that as long as the queue an MDB is listening to has enough messages, glassfish would create enough instances to parallel process the messages.

Am I missing something?
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