How to Configure the # of instances of an MDB

[sick1]

I would like to control the # of instances of MDB's in the same way that I can control the min/max # of connections associated with a DataSource. I've seen the question posted several times here but I didn't find a clear answer. I'd also be happy to be talked into a better setup but I've achieved success using raw JMS with this type of problem before.

I'm using JBoss 3.2.3 on WinXP/2000 with JRockit 1.4.1_03.

The issue that I have is that I have an MDB which watches a Queue that can get a sudden burst of messages. The MDB does some CMP calls in a transaction. I keep running out of connections (No ManagedConnections available within configured blocking timeout) because it seems JBoss keeps making more instances of the MDB to handle the messages in the Queue.

I can start looking for a 'magic' number of connections for the database/datasource but this seems to be pretty fragile. I'd much rather set a max of the # of MDB's that can be created.

Thanks,

Mike Sick

[adrian.brock]

There are two settings:

jboss.xml/invoker-proxy-bindings/invoker-proxy-binding/proxy-factory-config/MaximumSize
controls the number of concurrent jms sessions (default 15)

jboss.xml/container-configuations/container-configuration/container-pool-conf/MaximumSize
controls the number of MDB instances (default 100)

You will find all this information in docs/dtd/jboss_3_2.dtd

Here is something I added for 3.2.4 that provides a singleton MDB
http://cvs.sourceforge.net/viewcvs.py/jboss/jboss/src/etc/conf/default/standardjboss.xml?r1=1.47.2.15&r2=1.47.2.16

Regards,
Adrian

[geirwilly]

Is it possible to configure the max number of concurrent mdbs on i"ndividual" mdb-basis. Not as a global setting for all mdb's.

[yxyang]

hi, adrian

what is the relation between queue, MDBs which watch the queue, and threads are running the MDB codes?

I have a few MDBs (different class and do different businesses) which are watching a specific queue by using message selectors. I configed these MDBs to be singleton MDBs.
My question is : how many threads will be used by jboss to deliver the messages to these MDBs? What i expected is that each singleton MDB will has one thread. So, for this specific queue, there are a few threads to do the message delivering. Is this assumption correct?
Because if one queue has only one thread, then the performance will be decreased too much by employing singleton MDB.

Regards
yang

[joshlam]

There are two settings:

jboss.xml/invoker-proxy-bindings/invoker-proxy-binding/proxy-factory-config/MaximumSize
controls the number of concurrent jms sessions (default 15)

jboss.xml/container-configuations/container-configuration/container-pool-conf/MaximumSize
controls the number of MDB instances (default 100)

Hi Adrian,

Does the above work with xDoclet? I am using the jBoss IDE 1.2.2 within Eclipse 2.1.1 but it does not seem to recognize the xDoclet tag for container-configurations , container-pool-conf. Normally I would start with a @jboss. and then hit 'Control-space' to auto complete, when I do that it only recognizes a 'container-configuration' which has a name tag following.

Also, can I use the above configuration to configurate one instance of a particular MDB (while the rest uses the default value)?

Thanks.

--
Josh

[adrian.brock]

You define container configurations using a merge file
jboss-container.xml

Regards,
Adrian

[cvandyck]

Here is something I added for 3.2.4 that provides a singleton MDB
http://cvs.sourceforge.net/viewcvs.py/jboss/jboss/src/etc/conf/default/standardjboss.xml?r1=1.47.2.15&r2=1.47.2.16

Adrian

This is insanely useful and you have shaved hours off of the development of a feature I needed implemented today. Thank you.