Re: JVM on i-Series

400-600 jvms?  That's an incredible load!

We have had 2000 or so interactive jobs feeding requests into a data queue
with a couple of jvms running multithreaded apps (about 50 threads per jvm)
that make requests out to a webservice on another platform.  Replies have
been put onto a keyed data queue so that each interactive job can retrieve
their own response.

This has been very successful and does not tax the iSeries.  Another method
of RPG to java communication is sockets.

We isolated our jvms (we have several more running) into their own memory
pool.  With tuning on this you want to be sure to have enough memory
allocated to the pool.  You can check this through the STRSST.  There is an
option that allows one to see the last several garbage collections, GCCycles
(I can't remember the menu options - reply back if you need it).  This will
provide the size of the jvm.  As far as processes, you need to count each
thread and add some for the jvm for the number of concurrent processes.
This is usually more than enough since all the threads will probably not be
active all at once.  I will back this down a bit.

When setting up your java app, you need to watch the SQL performance (DBMon
in Ops Navigator) and also your jvm heap size.  On the heap size, you should
see a normal saw tooth pattern vs. a heap size that continually grows.  If
the latter happens, there is something in the app that is not releasing
memory and some further investigation is necessary with the dump jvm command
or the analyze jvm command.  If you are unable to determine the cause of the
growth you can use heap analyzer that is the free part of iDoctor.
Rochester support is very good and helping with these kinds of problems
also.

PatM
-----Original Message-----
From: wdsci-l-bounces@xxxxxxxxxxxx [mailto:wdsci-l-bounces@xxxxxxxxxxxx] On
Behalf Of Colin Williams
Sent: Wednesday, March 15, 2006 6:12 PM
To: Websphere Development Studio Client for iSeries
Subject: Re: [WDSCI-L] JVM on i-Series

400 to 600 JVMs!

Sacha, the background process attached to a dataqueue id definitely the way
to go, and that gives you the flexibility to add more JVMs listening to the
dataqueue as and when you need them to meet demand. Its very efficient this
way and does not overload the system


On 14/03/06, Sacha Boer <sachaboer@xxxxxxxxx> wrote:
>
> Thanks David,
>
> just subscribed.
>
> Sacha
>
> 2006/3/14, David Gibbs <david@xxxxxxxxxxxx>:
> > Sacha Boer wrote:
> > > do any of you have experience with java on the iSeries?
> >
> > This question would be better suited to the JAVA400-L list
> > (http://lists.midrange.com/listinfo/java400-l).
> >
> > david
> > --
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