Comments on: Playing with JVM / Java Heap Size.

By: Kellie B

Kellie B — Mon, 10 Oct 2011 10:02:01 +0000

I need to ‘increase java heap size in jvmcfg.ini’ I have no idea what this means but from the information above see I need to ‘Xmx set maximum Java heap size’, what does that mean I actually do? Cut and past that somewhere?

I have a macbook and am not down with computer lingo so would really love some basic straightforward instruction for dummies.

By: JigSaw

JigSaw — Thu, 29 Sep 2011 19:21:59 +0000

In Windows you should write it as;
java -Xms64m -Xmx1024m -jar MyProgram.jar

java -Xms64m -Xmx256m HelloWorld doesn’t work for me, I added -jar part and it works now.

By: Chris

Chris — Tue, 20 Sep 2011 02:55:54 +0000

There is a way to set this permanantly. In windows, go to control panel, click java, go to java tab, click view, and under runtime parameters put -Xmx4G or whatever size you want

By: Dala

Dala — Thu, 08 Sep 2011 20:58:16 +0000

I think it is not the real reason
bye

By: Dala

Dala — Thu, 08 Sep 2011 20:44:26 +0000

HI
I tried to increase the java heap size I used this command line:
java -Xmx1K
I have this error :
error occurred during initialization of VM
could not reserve enough space for object heap
could not create the java virtual machine
I search and found the reason of this error is Heap size is larger than my computer’s physical memory , and I don’t know if it the real reason is the physical memory , can any one help my to fixed this error .

By: rajesh.kolli

rajesh.kolli — Wed, 25 May 2011 08:54:14 +0000

you can read different parts of the heap on the following link:

http://java-espresso.blogspot.com/2011/05/heap-structure-in-jvm.html
Gist of the article is below:

Following are the parts in JVM heap:

Young Generation
Eden Space
Survivor space
Virtual space
Tenured (Old) generation:
Virtual Space
Other Areas: Not a part of heap:
PermGen Area
Native Area

http://viralpatel.net/blogs/2009/01/jvm-java-increase-heap-size-setting-heap-size-jvm-heap.html

http://hausheer.osola.com/docs/5

http://www.codemiles.com/java/here-how-to-increase-java-heap-size-t663.html

By: Dharmvir

Dharmvir — Mon, 16 May 2011 18:19:12 +0000

You can read about different parts of the heap on the following link:
http://java-espresso.blogspot.com/2011/05/heap-structure-in-jvm.html
Gist of the article is below:

Following are the parts in JVM heap:

Young Generation
Eden Space
Survivor space
Virtual space
Tenured (Old) generation:
Virtual Space
Other Areas: Not a part of heap:
PermGen Area
Native Area

By: rohini

rohini — Mon, 21 Feb 2011 10:58:42 +0000

same error bt solution not working……!

By: Dhana

Dhana — Tue, 21 Sep 2010 16:48:29 +0000

Hi All,

How to check what is teh heap size in a windows machine in command line?

By: rafikpbhdm

rafikpbhdm — Mon, 16 Aug 2010 13:03:34 +0000

hi my friends, well I tried to increase java heap space using run configuration in eclipse and netbeans, and the result was same ,I had NoClassDefFoundError , and when I deleted the command line (java -Xms64m -Xmx256m) and run the application again it worked normally except of course the pb of OutOfMemory exception, and even try dos prompt ,the vm didn’t recognize the option -Xmx and sometimes it just throw the excption NoClassDefFoundError,well it ‘s really weird thing and I don’t know how to explain it ,so little help will be nice.