Large JVM heap sizes under windows xp?
843811Sep 11 2004 — edited Aug 6 2006I have a windows XP Pro SP1 box with 2 GB of physical RAM. I am using the latest jdk, 1.4.2_05.
I understand that 32 bit windows by default allows 2 GB address space for each application, permanently reserving 2 GB for the OS. (There are also apparently special builds going back to win2k which have a special mode where applications can address 3 GB and the OS addresses 1 GB; if anyone knows how to turn this mode on under win xp please let me know.)
So, I should be able to allocate ~2 GB to the JVM (the number is slightly less than 2 GB due to overhead associated with each process in windows) using something like
-Xms1900m -Xmx1900m
as command line args to the java command.
But when I try the above it crashes with the error
Error occurred during initialization of VM
Could not reserve enough space for object heap
Experimentally, I found that the maximum value which works on my box is
-Xms1200m -Xmx1200m
which seems way smaller than it ought to be.
Doing a forum search, I found others who report similar issues, e.g.
http://forum.java.sun.com/thread.jsp?forum=136&thread=522506
But I did not find a decent solution or up to date discusssion.
Does anyone know with windows xp pro what the jvm memory limit is?
As part of my sun search, I came across the following old (circa 2000) but interesting bug report:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4358809
I have never heard of the rebase program before. Is it built into windows? Is it safe to use? Anyone ever try the command as described there?