RE: JVM initialization memory concerns..?

As far as I know you will get one JVM per interactive job that calls your
module.

Many people take the approach of building a small server job that can accept
requests on a data queue and return responses on a separate data queue.

This means that as long as you use keyed data queues you can have multiple
interactive jobs serviced by one server jvm job.

The server job I have built uses multiple java threads so it really does
serve multiple jobs at the same time. The best part is because the server is
waiting on data queues when there are no requests the server uses no CPU.

Just make sure it is running in a responsive subsystem!!

-----Original Message-----
From: java400-l-bounces@xxxxxxxxxxxx [mailto:java400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Jonathan Keeney
Sent: 22 April 2009 18:17
To: Java Programming on and around the iSeries / AS400
Subject: JVM initialization memory concerns..?

I have what feel like some very rookie questions about running Java apps on
i...but please keep in mind that I'm very much a rookie. :) Thanks in
advance for any advice you all have to offer. To give a little background,
I have a set of Java classes that build a transaction object and pass it to
an RMI service that calculates pricing information. To populate the
information in this transaction object, I've prototyped several methods in
these classes and am calling them directly from a new RPG module I created.
This module is intended to serve as a bridge between our legacy RPG code and
the new calculation service. It's functioning very well, but my concerns
relate more to performance. We're running V5R4 on a model 520, and we've
run the upgrade so that we can run under Java 1.5 (5722JV1 option 7).

- Am I right in thinking that a new JVM is initialized for each interactive
job that will be calling this new module? I've read that the JVM is
integrated with i5/OS in a unique way that makes it function differently
from JVMs in other OSes, but I'm not well-versed enough in these things to
understand the repercussions of that.
- If this is the case, is it reasonable to expect that our i5 would be
overly taxed by having a large number (25? 30?) of these jobs running at
once?
- Is there any way to initialize one JVM and have all these sessions share
it? Would that even be beneficial if it were possible?

Thanks again.