Re: [Condor-users] java machines with > 2gb

[Michael Rusch <mcrusch@xxxxxxxx>]

Thank you everybody, for all of your explanations and help and suggestions.
However, there seems to be a great deal of misunderstanding about my
problem:

I am not trying to use >2gb of heap space.

I am NOT trying to use >2gb of heap space.

I AM trying to get my machine to show up in the pool.

You'll note from my previous posts that I'm setting -Xmx1g

Yes, I realize that on a 64-bit machine I theoretically *could* address much
more than 2gb.  I also know that java on that machine works fine using heap
spaces of much more than 2gb, as I've tried it.  However, for Condor, I
don't care--I'm content with 1gb (a number that is a safe distance from any
artificially-imposed-by-java ~2gb limit as documented in the condor docs), I
just can't use it at all if it doesn't show up in the pool, and that's the
problem.  Even when I use the workaround from the manual, which works on the
32-bit machines, I still can't get the 64-bit machine into the pool.

Michael

> -----Original Message-----
> From: condor-users-bounces@xxxxxxxxxxx [mailto:condor-users-
> bounces@xxxxxxxxxxx] On Behalf Of Matt Hope
> Sent: Tuesday, September 16, 2008 5:48 AM
> To: Condor-Users Mail List
> Subject: Re: [Condor-users] java machines with > 2gb
> 
> On Mon, Sep 15, 2008 at 10:27 PM, Joe Meehean <jmeehean@xxxxxxxxxxx>
> wrote:
> > This issue has everything to do with 32 vs. 64-bit
> > operating systems.  With 32-bit OS's no process
> > can have more than a 3GB address space.  If you
> > need more than 2GB of Java heap space ensure you
> > are submitting your job to a 64-bit machine with a
> > 64-bit OS.  If you don't need more than 2GB's,
> > follow the workaround.
> 
> Technically extensions like AWE can allow this - I know of no JVM
> vendors that have bothered to do this (it would make heap management
> an absolute nightmare).
> 
> Also note that, even on 64bit operating systems many vm's actually
> still disallow more than 2GB (neither will the .Net runtime) for any
> single object on the heap, so if you're trying to stuff everything
> into one array (or hashtable which is a single array under the hood)
> then going over 2GB won't help.
> 
> To the OP: If you're trying to go over 2GB heap and don't get most of
> this discussion then you need to start doing some reading up. If you
> don't need it go with the workaround like Joe says
> 
> Matt
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