Java在64位jvm上内存不足

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.

Answer 1

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

Answer 2

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.