Re: One JVM for batch job

[MEovino@xxxxxxxxxxxxxxxxx]

Barbara,

Just to clarify, you're saying that once a JVM is started in a job, any RPG
program in that job will use that JVM, right?

And if that is indeed the case, what would I do if I wanted to use an
existing JVM that's in another job (to avoid the time it takes to create a
JVM)?  Have the Java program listen to a message queue?  Turn the Java
program into a socket server and listen for requests?

We're calling Java programs from RPG and it works pretty well, except for
the performance penalty you pay when you create the JVM.  For batch stuff
we haven't worried about it, but if we ever want to do anything
interactive, it might be a hindrance.

And while we're on the subject, how resource intensive is the JVM?  If I
have a few hundred users on 5250 terminals and each one has their own JVM,
is this going to be an issue?

Mike E.




                                                                                
                                                    
                      Barbara Morris                                            
                                                    
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Joe Pluta wrote:
> ...
> Another way is to use RPG to directly call the Java class.  If the RPG
> program doesn't end, I believe it will use the same JVM over and over,
> but I haven't played with that architecture much.
>

The lifetime of the JVM doesn't have anything to do with RPG.  RPG will
start a JVM, but it will never end it.  In V5R2, the JVM should ideally
only end when the job ends.  In V5R1, the JVM gets ended if any
activation group is ended, and it can also be explicitly ended.  The
activation group thing doesn't happen in V5R2, and also in V5R2 you
can't explicitly end the JVM.

Once the JVM is started in a job, any RPG program will use that JVM.

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