Java and Determinism

Re: Java and Determinism

Hi Ken,

I am not sure what you mean by the products being deterministic - that is
good thing that they are. But when you mention real time performance
and Java then I think I know what you mean. Java is not deterministic in
respect to real time performance issues since it has incremental garbage
collection; you never know the Java VM stops your thread to do some
garbage collection.

I am afraid I can not help you on your second question on whether or not
the standard Java products is going to improve on real time issues. I know that Real
Time Java tries to open op the Java VM allowing application programmers to
give more precise priorities to threads (wether it is a thread to be run
real time, exact time and some more I can not remember). Also allowing you
to specify the garbage collection algoritm. And some more I can not
remember - look it up if you are interested http://www.rtj.org/.

Best regards
Kristian

On Fri, 07 Nov 2003 18:51:38 -0800, Ken wrote:
[color=blue]
> Hi.
>
> I'm working on a real time software project. It's not embedded, but
> it certainly is considered at a minimum "soft" real time, since it
> results in aircraft being moved around.
>
> Some folks here are looking into using Java, JMS, JMX and J2EE. I'm
> concerned about this because I've heard there are problems with
> implementations of these standards being deterministic.
>
> Could someone explain if determinism is a problem with this product
> family, and if so, what the issues are?
>
> I'm assuming there is a problem, thus the work being done on Real Time
> Java--I just don't have a clear understanding of what the issues are.
>
> I guess a follow up question is does anyone know if determinism issues
> are being addressed for JMS, JMX or J2EE, so the could be used once
> Real Time Java implementations are readily available?
>
>
> Thanks so much!
>
> Ken
>
>
> ______________[/color]

Re: Java and Determinism

(cut)[color=blue]
> I am afraid I can not help you on your second question on whether or not
> the standard Java products is going to improve on real time issues. I know that Real
> Time Java tries to open op the Java VM allowing application programmers to
> give more precise priorities to threads (wether it is a thread to be run
> real time, exact time and some more I can not remember). Also allowing you
> to specify the garbage collection algoritm. And some more I can not
> remember - look it up if you are interested http://www.rtj.org/.[/color]
(cut)

Just wanted to add that garbage collection is not the problem in se.
Real time garbage collection is possible.
Whether it is available for Java now, I don't know.

v