about 64 bit OS's and Java

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5 total messages Started by Alan Shiers Fri, 30 May 2003 21:46

#539

Author: Alan Shiers
Date: Fri, 30 May 2003 21:46

12 lines
1406 bytes

Hi there,

I've been reading a lot lately about Intel's Itanium CPU and AMD's
latest release of Opteron CPU; both are intended for 64 bit operating
systems. I guess Microsoft will soon be releasing Windows 2003, which
from reports I've been getting, is supposed to support 64 bit processors
like the ones just mentioned.  

I was wondering how that affects the Java Virtual Machine? Is the JVM a
32 bit compiler?  Will Sun be introducing a 64 bit compiler for the JVM?

Alan

Re: about 64 bit OS's and Java

#540

Author: John McGrath TeamB
Date: Sat, 31 May 2003 04:13

22 lines
1655 bytes

On Fri, 30 May 2003 18:46:43 -0300, Alan Shiers wrote:

> I was wondering how that affects the Java Virtual Machine? 
> Is the JVM a 32 bit compiler?  Will Sun be introducing a 64 
> bit compiler for the JVM?

The Itanium and other 64-bit processors should have no effect on Java 
programs -- the function of the JVM is the same regardless of the 
platform that it runs on.

Sun has already released versions of the JVM for Windows and Linux 
64-bit systems running on the Itanium.  Note that this is essentially 
Beta software -- the license does not allow commercial use.

-- 
Regards,

John McGrath [TeamB]

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Re: about 64 bit OS's and Java

#541

Author: Alan Shiers
Date: Sat, 31 May 2003 16:36

34 lines
2104 bytes

Interesting...

When Windows2003 and other 64 bit OS's get released, will coding be
basically the same for the programmer, even though Microsoft, Borland,
and others may release 64 bit compilers?  I'm wondering to what
advantage a programmer can make use of programs intended for 64 bit
OS's?

Alan

"John McGrath [TeamB]" wrote:
> 
> On Fri, 30 May 2003 18:46:43 -0300, Alan Shiers wrote:
> 
> > I was wondering how that affects the Java Virtual Machine?
> > Is the JVM a 32 bit compiler?  Will Sun be introducing a 64
> > bit compiler for the JVM?
> 
> The Itanium and other 64-bit processors should have no effect on Java
> programs -- the function of the JVM is the same regardless of the
> platform that it runs on.
> 
> Sun has already released versions of the JVM for Windows and Linux
> 64-bit systems running on the Itanium.  Note that this is essentially
> Beta software -- the license does not allow commercial use.
> 
> --
> Regards,
> 
> John McGrath [TeamB]
> 
> ---------------------------------------------------
> Before sending me e-mail, please read:
>     http://www.JPMcGrath.net/newsgroups/e-mail.html

Re: about 64 bit OS's and Java

#542

Author: John McGrath TeamB
Date: Mon, 02 Jun 2003 04:33

29 lines
2139 bytes

On Sat, 31 May 2003 13:36:41 -0300, Alan Shiers wrote:

> Interesting...
> 
> When Windows2003 and other 64 bit OS's get released, will coding 
> be basically the same for the programmer, even though Microsoft, 
> Borland, and others may release 64 bit compilers?  

For Java programming, yes.  One of the central design ideas for Java is 
to isolate the programmer from differences in the underlying machine.  
Java code should run the same regardless of the underlying platform.

> I'm wondering to what advantage a programmer can make use of 
> programs intended for 64 bit OS's?

What is new about these machines that you would want to take advantage 
of?  I suspect that they will perform some operations faster (such as 
64-bit arithmetic), and the JVM for 64-bit machines should use the 
appropriate instructions to take advantage of that.  But there should 
not be any reason for the Java programmer to worry about that.

-- 
Regards,

John McGrath [TeamB]

---------------------------------------------------
Before sending me e-mail, please read:
    http://www.JPMcGrath.net/newsgroups/e-mail.html

Re: about 64 bit OS's and Java

#543

Author: Shankar Unni
Date: Mon, 02 Jun 2003 17:11

15 lines
1775 bytes

Alan Shiers wrote:

> I was wondering how that affects the Java Virtual Machine? Is the JVM a
> 32 bit compiler?  Will Sun be introducing a 64 bit compiler for the JVM?

You shouldn't have to worry. There may be separate 32-bit and 64-bit VMs 
(because the 64-bit VM is likely to be larger for the same size of 
program, simply because of the 64-bit vs 32-bit pointer issue), but that 
should be transparent to your program, unless it actually intends to use 
more than 2GB of heap.

By the way, it's likely that if you work with a 100GB heap, you will 
face painfully long full-GCs. If you have a single process that's 
growing that large, it may be time to split it into a bunch of smaller 
processes that work on subsets of the data in parallel.

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