Java out of memory on 64-bit jvm

Question

I have got a problem. My program is really big and java is throwing OutOfMemoryException. In .bat file, I have got the following:

java -server -Dfile.encoding=UTF-8 -Xmx1500m -Xbootclasspath/p:../libs/l2ft.jar -cp config/xml;../libs/*; l2ft.gameserver.GameServer

Java is using 6 GB of my RAM, next 6 GB is not used.

I typed System.getProperty("sun.arch.data.model"); and it says that I am using 64-bit JVM.

Try increasing Xmx (max heap). Your current setting is a just under 1.5GB. — John Watts
– John Watts, Commented Sep 16, 2012 at 14:09
How do you know that it is using 6GB of RAM? and what do you mean by "next 6 GB is not used"? — Vikdor
– Vikdor, Commented Sep 16, 2012 at 14:09

Peter Lawrey · Accepted Answer · 2012-09-16 14:08:44Z

4

You have set the maximum heap size to 1500m and while the JVM can use a little more than that ~200 MB, that's all you limited the process to.

Try instead to limit your progress to around 5 GB. (You want to leave some memory for overhead and the OS)

-mx5g

answered Sep 16, 2012 at 14:08

Peter Lawrey

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Comments

Maurício Linhares · Accepted Answer · 2012-09-16 16:17:17Z

0

Make the options before Xbootclasspath this:

java -XX:MaxPermSize=512m -server -Dfile.encoding=UTF-8 -Xmx8g -XX:+UseCompressedOops

This will make it use more memory and will also make sure it uses as little memory as possible to address the objects in a 64bits machine.

The -XX:MaxPermSize=512m makes the perm gem space larger (which you will probably need as you're using a lot of heap memory) and the -XX:+UseCompressedOops will make it use 32bits addressing for objects, instead of 64bits, as a 8gb heap can be correctly addressed with 32bits, so it makes you use less memory for allocating objects.

edited Sep 16, 2012 at 16:17

answered Sep 16, 2012 at 14:14

Maurício Linhares

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3 Comments

LanguagesNamedAfterCofee Over a year ago

I'm curious, why did this get downvoted? Is there something wrong with this answer?

Maurício Linhares Over a year ago

Who knows? There was another answer that was also correct and got downvoted. Looks like the owner deleted it.

Nikem Over a year ago

IMHO setting MaxPermSize in this case is somewhat premature opitimization. There is no indication so far, that topic starter suffers from insufficient PermGen.

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