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----- Original Message -----
From: "Robert S. Sfeir" <[EMAIL PROTECTED]>
To: "Orion-Interest" <[EMAIL PROTECTED]>
Sent: Wednesday, July 25, 2001 11:09 PM
Subject: RE: Orion Performance Tuning
> At 12:49 PM 7/25/2001, Duffey, Kevin wrote:
> >I am interested in your two fixes. Have you (or anyone) noticed that
Orion
> >actually requires 175MB of RAM?
>
> I think it's mainly our Servlet that uses this up. I think it depends on
> how many servlets you load.
>
> > Is there a definite need to use both memory
> >switches, or perhaps one over the other? What is the use and/or meaning
of
> >each switch?
>
> -Xms = minimum amount of memory the JVM will use
> -Xmx = mazimum amount of memory the JVM will use
>
> > What I find funny is I just installed JDK 1.3.1 and noticed the
> >/server, /classic and /hotspot dirs under bin which contain the jvm.dll
that
> >Windows uses. I was actually going to post an email to this and JSP
interest
> >list asking what the benefits and differences are between the 3 jvms.
>
> BIG benefits, just try it.
>
The hotspot IS included in JDK1.3.1, so the -hotspot switch is not needed.
Anyhow, the difference between -client and -server switches is the 80-20
model and a more dynamic OSR ( on stack replacement ).
The client option uses a static 80-20 model to determine which methods are
to be marked as HOT and therefore subject to OSR. The server option however
determines OSR at runtime marking methods over a period of time, doing
statistics whatever to truly determine how and why and when to do OSR. The
client starts immediately and is used for programs that run from a couple of
minutes to a day approx, and the 80-20 approach is applicable and "enough
for client needs". The server on the other hand requires at least a few
hours uptime to determine which methods are HOT. This information is lost on
System.exit(int), so, at every restart it has to do all statistics again.
But then, a server jvm should not be restarted.
For development I would (and do) use -client so I can stop and start the
server more often without wait for statistics.
The difference is the internal compiler. They are completely different. The
server compiler was written from scratch. And for all I know the compiler is
not completely finished, and use the client compiler where it does not know
how to handle something. So SUN has only released the "safe" compiler and
there should not be a need to use -server on development since behaviour
will be the same, only time wont.
Johan
> > I
> >haven't been able to find anything on the sun site that details how they
are
> >different. Can you fill me in if you know, what makes the server jvm
better?
>
> From what I understand, it uses memory and processors more efficiently,
> more driven for background apps rather than a client JVM driven with
> foreground apps in mind.
>
> >Is it better overall for all use (other than client-side SWING apps)? I
> >thought the hotspot was the best because of the inline JIT that converts
> >code to native..and thus should speed it up greatly. Is the server better
> >just for production use, or for anyone running Orion locally for web
> >development as well? Ideally, I would think we want our development, qa,
> >staging and live servers to all run the same JVM to make sure we all see
any
> >problems that arise.
>
> I use it for everything here now. No harm, just benefits, you just gotta
> have the RAM.
>
> R
>
>
> Robert S. Sfeir
> Director of Software Development
> PERCEPTICON corporation,
> in Joint Venture With JTransit
> San Francisco, CA 94123
> pw - http://www.percepticon.com/
> jw - http://jtransit.com
> e- [EMAIL PROTECTED]
>
