Hi all,
On 32bit JVM's I've never had luck going over 2GB of heap, including
tweaking OS parameters. My current project has a few dual x64 machines
running on XP (not linux unfortunately) . Anyways, our app uses more
memory via the JVM than processor, and the 2GB JVM heap limit is
reached far earlier than the dual x64 processors rise above 50%
capacity.
I noticed Java 6 64bit JVM support for XP x64 - intel. Does anyone know
if for example I have 8GB of memory . I can raise the max heap size to
6GB ? The example assumes nothing else on the machine, just running
jboss / hibernate and uses lots of memory. I'm asking because before I
recommending purchasing more memory, I can use it. I did a lot of
googling but didn't turn up any specifics.
Robert
Patricia Shanahan - 29 Dec 2006 16:53 GMT
> Hi all,
>
[quoted text clipped - 13 lines]
>
> Robert
A 64-bit JVM, given sufficient physical memory, does remove the 2 GB
heap limit. I don't know what the effective limit will be for your
configuration.
Maybe, if nobody does know specifically, you could test by borrowing
memory, or getting access to a similar system with more memory?
Patricia
Arne Vajhøj - 29 Dec 2006 17:25 GMT
> On 32bit JVM's I've never had luck going over 2GB of heap, including
> tweaking OS parameters. My current project has a few dual x64 machines
[quoted text clipped - 9 lines]
> recommending purchasing more memory, I can use it. I did a lot of
> googling but didn't turn up any specifics.
http://www.theserverside.net/tt/articles/showarticle.tss?id=NET2BMNov64Bit#_Toc1
04911912
Are running WAS 6.0 with 14.5 GB heap size on both Windows 2003
64 bit and Redhat Linux 64 bit.
That is with IBM JVM.
http://www.spec.org/jbb2005/results/res2006q3/jbb2005-20060815-00179.txt
3.7 GB heap size with JRockit JVM.
>2 GB has been seen.
Arne
Daniel Pitts - 30 Dec 2006 07:42 GMT
> Hi all,
>
[quoted text clipped - 13 lines]
>
> Robert
I might recommend trying to find a way to reduce your memory
requirements. I know its not always possible, but sometimes a tweak in
any algorithms you use might help signifigantly. Using lazy loading in
hibernate might help some, and possibly throttling usage, or
distributing usage via a load-balancer might be useful too.