RE: [OT] How much RAM can java use [255767:132281]

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> -Original Message-
> From: "Edmon Begoli" <[EMAIL PROTECTED]>
> Received: 10/7/2005 3:50 PM
> To: 
> Subject: RE: [OT] How much RAM can java use
>
> I asked this same question Cameron Purdy, CEO of Tangosol (maker of a 
> leading Java cache product) this question during the TheServerSide this 
> year.
> His business is all about optimal use of the allocated heap space, and that
> 
> His recommendation was to use up to 512 MB of heap space to minimize 
> more severe garbage collection pauses.
> I think that this article Java 5.0 JVM tuning 
> <http://java.sun.com/docs/hotspot/gc5.0/gc_tuning_5.html> can help you 
> answer what is the optimal use.
> 
> 
> 
> 
> On 10/6/05, Caldarale, Charles R <[EMAIL PROTECTED]> wrote:
> 
> >>> > From: Leon Rosenberg [mailto:[EMAIL PROTECTED]
> >>> > Subject: [OT] How much RAM can java use
> >>> >
> >>> > Does anyone know for sure how much RAM I can use with JAVA 1.4 or 1.5?
> >>
> >>
> 
> 

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RE: [OT] How much RAM can java use

[Edmon Begoli]

I asked this same question Cameron Purdy, CEO of Tangosol (maker of a 
leading Java cache product) this question during the TheServerSide this 
year.

His business is all about optimal use of the allocated heap space, and that

His recommendation was to use up to 512 MB of heap space to minimize 
more severe garbage collection pauses.
I think that this article Java 5.0 JVM tuning 
 can help you 
answer what is the optimal use.





On 10/6/05, Caldarale, Charles R <[EMAIL PROTECTED]> wrote:


> From: Leon Rosenberg [mailto:[EMAIL PROTECTED]
> Subject: [OT] How much RAM can java use
>
> Does anyone know for sure how much RAM I can use with JAVA 1.4 or 1.5?
   

RE: [OT] How much RAM can java use

[Mark Benussi]

This was probably one of the best threads I have 'listened' to in ages. I am
researching setting up my own Tomcat hosting. This is going to be of use.

-Original Message-
From: Leon Rosenberg [mailto:[EMAIL PROTECTED] 
Sent: 06 October 2005 20:48
To: Tomcat Users List
Subject: Re: [OT] How much RAM can java use

Chuck, Ryan,

thanx, you were extremely helpful!

regards
Leon

On 10/6/05, J. Ryan Earl <[EMAIL PROTECTED]> wrote:
> Leon Rosenberg wrote:
>
> >Debian 3.1, kernel 2.6.x-smp (32 bit)
> >or
> >Debian 3.1, kernel 2.6.x-smp-emt64 (64 bit)
> >
> >Hardware: AMD Opteron and Xeon64 (both 64 bit)
> >
> >SUN jdk1.5 and/or jdk1.4.2
> >
> >4 GB total RAM for 32-bit linux, with 3/1 memory partitioning
> >16GB total RAM for 64-bit linux.
> >
> >
> I've tested 32/64 bit JVMs extensively and done considerable amount of
> JAVA_OPTS tuning for my company's application.  On a 32-bit machine you
> can't reliably go above a -Xms=1600m without getting OOM errors.  With a
> 3/1 split your virtual page table size for the entire JVM process must
> be below 3GB total virtual memory.  That's 3GB allocated, not commited.
> The JVM allocates a lot more memory besides the heap.
>
> With the 64-bit JVMs, the sky's the limit, however the 64-bit address
> also make your application take up more space relative to a 32-bit JVM.
> A 3.2GB 64-bit heap space isn't going to double the amount of identical
> objects you can create as compared to a 32-bit 1.6GB heap space because
> all pointer references will occupy twice the space.
>
> -ryan
>
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Re: [OT] How much RAM can java use

[Leon Rosenberg]

Chuck, Ryan,

thanx, you were extremely helpful!

regards
Leon

On 10/6/05, J. Ryan Earl <[EMAIL PROTECTED]> wrote:
> Leon Rosenberg wrote:
>
> >Debian 3.1, kernel 2.6.x-smp (32 bit)
> >or
> >Debian 3.1, kernel 2.6.x-smp-emt64 (64 bit)
> >
> >Hardware: AMD Opteron and Xeon64 (both 64 bit)
> >
> >SUN jdk1.5 and/or jdk1.4.2
> >
> >4 GB total RAM for 32-bit linux, with 3/1 memory partitioning
> >16GB total RAM for 64-bit linux.
> >
> >
> I've tested 32/64 bit JVMs extensively and done considerable amount of
> JAVA_OPTS tuning for my company's application.  On a 32-bit machine you
> can't reliably go above a -Xms=1600m without getting OOM errors.  With a
> 3/1 split your virtual page table size for the entire JVM process must
> be below 3GB total virtual memory.  That's 3GB allocated, not commited.
> The JVM allocates a lot more memory besides the heap.
>
> With the 64-bit JVMs, the sky's the limit, however the 64-bit address
> also make your application take up more space relative to a 32-bit JVM.
> A 3.2GB 64-bit heap space isn't going to double the amount of identical
> objects you can create as compared to a 32-bit 1.6GB heap space because
> all pointer references will occupy twice the space.
>
> -ryan
>
> -
> To unsubscribe, e-mail: [EMAIL PROTECTED]
> For additional commands, e-mail: [EMAIL PROTECTED]
>
>

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Re: [OT] How much RAM can java use

[J. Ryan Earl]

Leon Rosenberg wrote:


Debian 3.1, kernel 2.6.x-smp (32 bit)
or
Debian 3.1, kernel 2.6.x-smp-emt64 (64 bit)

Hardware: AMD Opteron and Xeon64 (both 64 bit)

SUN jdk1.5 and/or jdk1.4.2

4 GB total RAM for 32-bit linux, with 3/1 memory partitioning
16GB total RAM for 64-bit linux.
 

I've tested 32/64 bit JVMs extensively and done considerable amount of 
JAVA_OPTS tuning for my company's application.  On a 32-bit machine you 
can't reliably go above a -Xms=1600m without getting OOM errors.  With a 
3/1 split your virtual page table size for the entire JVM process must 
be below 3GB total virtual memory.  That's 3GB allocated, not commited.  
The JVM allocates a lot more memory besides the heap.


With the 64-bit JVMs, the sky's the limit, however the 64-bit address 
also make your application take up more space relative to a 32-bit JVM.  
A 3.2GB 64-bit heap space isn't going to double the amount of identical 
objects you can create as compared to a 32-bit 1.6GB heap space because 
all pointer references will occupy twice the space.


-ryan

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RE: [OT] How much RAM can java use

[Caldarale, Charles R]

> From: Leon Rosenberg [mailto:[EMAIL PROTECTED] 
> Subject: Re: [OT] How much RAM can java use
> 
> > I've seen 64-bit Sparc systems with Java heaps sized at hundreds of
> > megabytes...

Oops, I meant hundreds of _gigabytes_ (just a slight miscalculation :-).

With the 32-bit Sun JVM, you're not going to get much more than 1.2 GB
you're at now, primarily due to the contiguous heap requirement and the
use of signed 32-bit integers within the HotSpot heap manager.  To take
advantage of the 64-bit platforms, you'll need to install a true 64-bit
JVM, which is a separate download from the normal JRE/JDK.  With that,
you should be able to use pretty much all of the RAM, minus the system
overhead.  The key issue is insuring that the 64-bit Debian provides a
decent amount of virtual space for each process.

 - Chuck


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RE: [OT] How much RAM can java use

[Dale, Matt]

On the 32 bit system you definitely won't get more the 2G without some kernel 
hacking and you may well see even less than that.

On the 64 with a 64 bit JVM you should be able to use however much you like 
obviously leaving some space for the OS to run in.

-Original Message-
From: Leon Rosenberg [mailto:[EMAIL PROTECTED]
Sent: 06 October 2005 17:16
To: Tomcat Users List
Subject: Re: [OT] How much RAM can java use


On 10/6/05, Caldarale, Charles R <[EMAIL PROTECTED]> wrote:
> > From: Leon Rosenberg [mailto:[EMAIL PROTECTED]
> > Subject: [OT] How much RAM can java use
> >
> > Does anyone know for sure how much RAM I can use with JAVA 1.4 or 1.5?
>
> The answer is very platform specific.  For example, on a normal 32-bit
> Windows system, each process has a maximum of 2 GB to play with, but
> some of that is taken up by various .dlls.  (And unfortunately, these
> are scattered throughout the range, and the Sun JVM insists on having
> contiguous space for the heap.)  There is a boot option for some
> versions of Windows Server that changes the process virtual space to 3
> GB, at the expense of some kernel capacity.
>
> I've seen 64-bit Sparc systems with Java heaps sized at hundreds of
> megabytes...

Ok, I'll try to be more specific:

Debian 3.1, kernel 2.6.x-smp (32 bit)
or
Debian 3.1, kernel 2.6.x-smp-emt64 (64 bit)

Hardware: AMD Opteron and Xeon64 (both 64 bit)

SUN jdk1.5 and/or jdk1.4.2

4 GB total RAM for 32-bit linux, with 3/1 memory partitioning
16GB total RAM for 64-bit linux.

thanx
leon

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Re: [OT] How much RAM can java use

[Leon Rosenberg]

On 10/6/05, Caldarale, Charles R <[EMAIL PROTECTED]> wrote:
> > From: Leon Rosenberg [mailto:[EMAIL PROTECTED]
> > Subject: [OT] How much RAM can java use
> >
> > Does anyone know for sure how much RAM I can use with JAVA 1.4 or 1.5?
>
> The answer is very platform specific.  For example, on a normal 32-bit
> Windows system, each process has a maximum of 2 GB to play with, but
> some of that is taken up by various .dlls.  (And unfortunately, these
> are scattered throughout the range, and the Sun JVM insists on having
> contiguous space for the heap.)  There is a boot option for some
> versions of Windows Server that changes the process virtual space to 3
> GB, at the expense of some kernel capacity.
>
> I've seen 64-bit Sparc systems with Java heaps sized at hundreds of
> megabytes...

Ok, I'll try to be more specific:

Debian 3.1, kernel 2.6.x-smp (32 bit)
or
Debian 3.1, kernel 2.6.x-smp-emt64 (64 bit)

Hardware: AMD Opteron and Xeon64 (both 64 bit)

SUN jdk1.5 and/or jdk1.4.2

4 GB total RAM for 32-bit linux, with 3/1 memory partitioning
16GB total RAM for 64-bit linux.

thanx
leon

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RE: [OT] How much RAM can java use

[Caldarale, Charles R]

> From: Leon Rosenberg [mailto:[EMAIL PROTECTED] 
> Subject: [OT] How much RAM can java use
> 
> Does anyone know for sure how much RAM I can use with JAVA 1.4 or 1.5?

The answer is very platform specific.  For example, on a normal 32-bit
Windows system, each process has a maximum of 2 GB to play with, but
some of that is taken up by various .dlls.  (And unfortunately, these
are scattered throughout the range, and the Sun JVM insists on having
contiguous space for the heap.)  There is a boot option for some
versions of Windows Server that changes the process virtual space to 3
GB, at the expense of some kernel capacity.

I've seen 64-bit Sparc systems with Java heaps sized at hundreds of
megabytes...

 - Chuck


THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY
MATERIAL and is thus for use only by the intended recipient. If you
received this in error, please contact the sender and delete the e-mail
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RE: [OT] How much RAM can java use

[Dale, Matt]

Hi,

This will depend on which architecture of machine you are using. You will need 
both a 64 bit machine and a 64bit JVM to use that much memory. We use 12GB here 
with no problems on 64 bit solaris.

Ta
Matt

-Original Message-
From: Leon Rosenberg [mailto:[EMAIL PROTECTED]
Sent: 06 October 2005 16:53
To: Struts Users Mailing List; Tomcat Users List
Subject: [OT] How much RAM can java use


Sorry for off-topic, but there are so many experts here! :-)

Does anyone know for sure how much RAM I can use with JAVA 1.4 or 1.5?
It seems to me, that the VM don't use more than 1.2 GB RAM even I gave
it more (with mx/ms settings). We are planning to go to 16GB RAM
machines to have a better caching, but I started to doubt that I can
use 16GB Ram in a single JVM.

Any thoughts, anyone?

thanx
leon

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