Limitation on 1.5 heap size using -Xmx
843829Aug 15 2007 — edited Aug 17 2007Hello,
We recently upgraded our application server and development server to 4GB and 3GB of RAM, respectively. Both run Windows Server 2003 Standard Edition SP2. We are using Java HotSpot Client VM 1.5.0_07.
When running our app, we wanted to increase the JVM heap size to 2.5GB. We tried to do this using the -Xmx switch in our Tomcat service setup, but received a JVM error:
"could not reserve enough space for object heap"
We found that we couldn't even get it up to 2GB (it's currently set at 1.5GB).
I did some research online, and found some information on increasing the windows virtual address space, using the /3GB switch in boot.ini; but I also found an old article (August 2000) suggesting that it might not help:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4358809
I saw articles mentioning rebasing DLLs to increase the contiguous heap space, but we would prefer to avoid that level of meddling if it's possible - and I can't find decent documentation for the rebase tool.
How can we increase our JVM heap size? Will the /3GB switch help? Can we use a different JVM (64-bit?) without upgrading our hardware? I appreciate any light that the Sun community can shed on the subject.
Thanks in advance for any help you can offer,
Russell Morrisey