[jboss-user] [Messaging, JMS & JBossMQ] - Re: maxMessages

[Renen]

I am probably confused. ;-) I generally am. 

I think sessions worked the way you suggest in previous versions of JBoss / EJB. I read maxSessions to refer to the number of threads that can deliver messages to the queue at a time:

anonymous wrote : 
  | the maximum number of jms sessions that can concurrently deliver messages to this mdb - default 15
  | 

maxMessages definitely controls the number of MDBs instantiated, and there is a one-to-one correlation between messages being processed, and MDBs instantiated. Ie, setting maxMessages to 4 results in messages being processed 4 at a time.

What I didn't do last night was set maxMessages to a number greater than maxSessions. So I just set maxMessages to 20: 20 MDBs where instantiated, and 20 messages where processed at a time (in fact, I sent through more than 20 messages - they where still processed 20 at a go).

I have just run the test a different way. Last night I set the MDBs to simply iterate through a simple for loop until 10 seconds had passed. This evening I ran the test calling a database query that took ten seconds to elapse (so, in theory, perhaps the MDB could yield its thread to be used by another message call). The results where the same: there is a one-to-one correspondence between maxMessages, and message throughput (which I think is a good thing!).

And, there doesn't seem to be a pool size setting anymore. Its not reflected in ConfigJMSMessageListener, and JBoss throws an error if you try to set it.

I do need to mess with these settings: our resource constraints lie in the database, not in JBoss. I need to be able to control the throughput to ensure that the database does not get overwhelmed.

I would very much like to get better clarity on the definition of maxSession and maxMessages, so if anybody can shed any light, I'm listening!

View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4093707#4093707

Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4093707