Memory settings.

[th-dev at onlinehome.de (Timo Hoepfner)]

>
> 2. I tried setting to: Xmx2048m Xms128m (also tried Xmx3g Xms1g) but 
> this seems not possible. I app wouldn't start up and I get this error 
> message in webobjects.err:
>
> "Could not reserve enough space for object heap
> Error occurred during initialization of VM"
>

 From Apple's java-dev mailing list 
(http://lists.apple.com/archives/java-dev/2003/Dec/msg00000.html):

> Subject: Re: Allocating more than 2G heap for JVM
> From: email@hidden
> Date: Mon, 01 Dec 2003 08:38:32 -0800
>
>  email@hidden wrote:
>  | If I perform the command:
>  | java -Xmx3G -version
>  |
>  | the result is:
>  | Error occurred during initialization of VM
>  | Could not reserve enough space for object heap
>  | Trace/BPT trap
>  |
>  | Does anybody know how to make it work?
>
>  Wait until there's a version of Java that uses 64-bit addresses. (It 
> probably won't exist until at least 10.4. Right now, everything but 
> the OS itself is limited to 32-bit addresses.) The addresses Java 
> currently uses aren't large enough to handle more than 2GB. (And a 
> sizable chunk of that 2GB is already reserved for various uses.)
>
>  Glen Fisher
>

I just tried it. The actual limit seems to be 1932m:

[pbg4:/] th% uname -a
Darwin pbg4.local 7.7.0 Darwin Kernel Version 7.7.0: Sun Nov  7 
16:06:51 PST 2004; root:xnu/xnu-517.9.5.obj~1/RELEASE_PPC  Power 
Macintosh powerpc
[pbg4:/] th% java -Xmx1932m -version
java version "1.4.2_05"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_05-141.3)
Java HotSpot(TM) Client VM (build 1.4.2-38, mixed mode)
[pbg4:/] th% java -Xmx1933m -version
Error occurred during initialization of VM
Could not reserve enough space for object heap
Trace/BPT trap
[pbg4:/] th%

Just tried it on a Sun Fire V440 with 8GB RAM. The limits are higher 
there. Intrestingly enough the messages of the JVM change there when 
approaching the limit... Here's the result:

bash-2.05$ uname -a
SunOS dudp 5.9 Generic_117171-09 sun4u sparc SUNW,Sun-Fire-V440
bash-2.05$ java -Xmx3924m -version
java version "1.4.1_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1_06-b01)
Java HotSpot(TM) Client VM (build 1.4.1_06-b01, mixed mode)
bash-2.05$ java -Xmx3925m -version
Fatal: Unable to create signal thread (may be due to resource limit)
Abort (core dumped)
...
bash-2.05$ java -Xmx3929m -version
Error occurred during initialization of VM
Could not reserve enough space for heap offset array
...
bash-2.05$ java -Xmx3933m -version
Error occurred during initialization of VM
Could not reserve enough space for card marking array
...
bash-2.05$ java -Xmx3945m -version
Error occurred during initialization of VM
Could not reserve enough space for object heap


Timo