How can I give eclipse more memory than 512M?

Question

I have following setup, but when I put 1024 and replace all 512 with 1024, then eclipse won't start at all. How can I have more than 512M memory for my eclipse JVM?

-startup
plugins/org.eclipse.equinox.launcher_1.0.201.R35x_v20090715.jar
--launcher.library
plugins/org.eclipse.equinox.launcher.win32.win32.x86_1.0.200.v20090519
-product
com.springsource.sts.ide
--launcher.XXMaxPermSize
512M
-vm
C:Program Files (x86)Javajdk1.6.0_18injavaw 
-vmargs
-Dosgi.requiredJavaVersion=1.5
-Xms512m
-Xmx512m
-XX:MaxPermSize=512m

Answer 1

I've had a lot of problems trying to get Eclipse to accept as much memory as I'd like it to be able to use (between 2 and 4 gigs for example).

Open eclipse.ini in the Eclipse installation directory. You should be able to change the memory sizes after -vmargs up to 1024 without a problem up to some maximum value that's dependent on your system. Here's that section on my Linux box:

-vmargs
-Dosgi.requiredJavaVersion=1.5
-XX:MaxPermSize=512m
-Xms512m
-Xmx1024m

And here's that section on my Windows box:

-vmargs
-Xms256m
-Xmx1024m

But, I've failed at setting it higher than 1024 megs. If anybody knows how to make that work, I'd love to know.

EDIT: 32bit version of juno seems to not accept more than Xmx1024m where the 64 bit version accept 2048.

EDIT: Nick's post contains some great links that explain two different things:

• The problem is largely dependent on your system and the amount of contiguous free memory available, and
• By using javaw.exe (on Windows), you may be able to get a larger allocated block of memory.

I have 8 gigs of Ram and can't set -Xmx to more than 1024 megs of ram, even when a minimal amount of programs are loaded and both windows/linux report between 4 and 5 gigs of free ram.