[Building Sakai] JAVA_OPTS issue

[Steve Swinsburg]

Hi,

This is most likely to do with a 32 bit JVM.

Why can't I get a larger heap with the 32-bit JVM?

The maximum theoretical heap limit for the 32-bit JVM is 4G. Due to various additional constraints such as available swap, kernel address space usage, memory fragmentation, and VM overhead, in practice the limit can be much lower. On most modern 32-bit Windows systems the maximum heap size will range from 1.4G to 1.6G. On 32-bit Solaris kernels the address space is limited to 2G. On 64-bit operating systems running the 32-bit VM, the max heap size can be higher, approaching 4G on many Solaris systems.

As of Java SE 6, the Windows /3GB boot.ini feature is not supported.

If your application requires a very large heap you should use a 64-bit VM on a version of the operating system that supports 64-bit applications. See Java SE Supported System Configurations for details.


ref: http://www.oracle.com/technetwork/java/hotspotfaq-138619.html#gc_oom

cheers,
Steve


On 24/01/2011, at 5:16 PM, Shoaib Chaudhary wrote:

> Dear All, 
> 
> I am using Tomcat 5.5.31 from JVM 6 on Windows server 2003 Enterprise Edition. I have made Virtual machine with 2.5 GB RAM. Original System RAM is 4 GB. but when I set JAVA_OPTS XMX value more then 1175 tomcat doesn't run. Can any one help me out in this regards. I want to utilize whole 4 GB memory of my machine for deploying Sakai 2.7.1. What are the maximum value for Java_opts parameters.  
> 
> Regards 
> MUHAMMAD SHOAIB | Software Engineer  
> National University of Computer and Emerging Sciences
> A. K. Brohi Road (Near Police Line) H11/4 Islamabad 
> Tel +92-(51)-111-128-128 Ext 344  Cell +92-(334)-5577712
> muhammad.shoaib at nu.edu.pk 
> 
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