[geeks] Upper Memory Limit - Java

[Francois Dion]

On Jan 30, 2008 2:26 PM, Brian Dunbar <brian.dunbar at liftport.com> wrote:
> > On Tue, Jan 29, 2008 at 01:56:46PM -0800, Brian Dunbar wrote:
> >
> > | We have an EDI program (it's new) that blows up when 'many large files'*
> > | are run through it.
> > |
> > | But I'm not here to complain about that.  During troubleshooting the
> > | vendor rep mentioned that Java has an upper memory limit and you can't
> > | allocate any more memory to it than X.
> > |
> > | Indeed we're giving the JVM 3850m of ram on startup
> > |
> > | /vendor-dir/bin/java -Xms3850m -Xmx3850m
> > |
> > | And it won't start with any more than that.
> > |
> > | But .. an upper memory limit on Java?  I can believe there is a point
> > past
> > | where it's simply not wise to allocate ram but .. is she mis-informed?
> >
> > No, she's not.  Though it's generally not about `not being wise' -- it
> > just breaks.
> >
> > 32 bit JVMs tend to blow up with -Xmx set at 2 GB or higher.  Of
> > course, in general, on a 32 bit platform, no process can allocate more
> > than 4 GB of memory, and your OS has to jump through some hoops to
> > even have that much memory available.
> >
> > For 64 bit JVMs, I don't know.  I would expect any hard coded memory
> > limits to be huge, but I haven't really done much with them.
> >
> > I'm surprised you can get up to 3850m -- but no higher.  Which JVM is
> > that?
>
> 1.5
>
> > What OS, platform?
>
> # uname -a
> SunOS hostname.company.com 5.10 Generic_118833-36 sun4u sparc
> SUNW,Sun-Fire-V240
>
> --
> Brian Dunbar

just as I hit reply... so yes your setup is normal with a 32 bit jvm.