RE: JVM initialization memory concerns..?

Jonathan Keeney writes:

I have what feel like some very rookie questions about running Java

[snip]

but my concerns relate more to performance.

Try this link, IBM's Performance Capabilities Reference Guide, V5R4:

http://publib.boulder.ibm.com/infocenter/iseries/v5r4/topic/books/sc410607.pdf

Here's V5R3 if that's more relevant for you:

http://publib.boulder.ibm.com/infocenter/iseries/v5r3/topic/books/sc410607.pdf

In both versions, Chapter 7 covers Java.

[snip]

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.

See the above link(s) as a good start.

- 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?

The usual answer applies here: It depends (on what they are doing).

- Is there any way to initialize one JVM and have all these sessions share
it? Would that even be beneficial if it were possible?

The short answer here is "Java threading" but if that isn't enough of a
hint by itself, you probably need to learn more about threading and then
apply that to your application's structure. On the whole, threading can
be a benefit. On the other hand, if your application does (e.g.) heavy
SQL or heavy native DB processing, you may not see much of a difference.


Larry Loen
Application Performance Group