Re: AS/400 and Java

["Mark Phippard" <MarkP@xxxxxxxxxxxxxxx>]

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Yes.  So obviously it is most suitable to long-running "server" type
applications that remain running.  Things like WebSphere and Tomcat.

That being said, the overhead of a JIT compile is much less than that of
CRTJVAPGM.  It is going over my head to go into specifics, but the way it
was explained to me was that at runtime the "compiler" has a lot more
information about how the code is being used so it can perform more
aggressive optimizations as well as the opposite, meaning it can no that
the code should probably just be interpreted.  The JIT compile can choose
to optimize just the pieces of your code that it wants to optimize based
on its algorithms.  It can also do some of the work in the background as
it learns more.

If you had some Java code that you were going to call in-line from an
interactive green screen process, then CRTJVAPGM would probably make more
sense since you would probably want minimal overhead.  But in long-running
processes, the JIT is a great option.

Mark








"David Gibbs" <david@midrange.com>
Sent by: java400-l-admin@midrange.com
11/04/2002 10:31 AM
Please respond to java400-l


        To:     java400-l@midrange.com
        cc:
        Subject:        Re: AS/400 and Java


"Mark Phippard" <MarkP=sC2JmdVpHGPwvR0lvYjcXw@public.gmane.org> wrote in
message
news:OF707E3787.1B823048-ON85256C67.0053B923-85256C67.00546169@softlanding.c
om...
> Actually most of the IBM'ers I have heard speak about this issue say
that
> the JIT compiler is the direction of the future.  It already produces
code
> that is comparable to optimization level 40 and will only get better.

But do you encounter the code generation overhead every time your class is
invoked?

david




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