Increase heap size in Java

Question

I am working on a Windows 2003 server (64-bit) with 8 GB RAM. How can I increase the heap memory maximum? I am using the -Xmx1500m flag to increase the heap siz

Answer 1

Several people pointed out the specific answers for heap size with the jvm options of -Xms and -Xms. I want to point out that this is not the only type of memory options for the jvm. Specifically if you are get stack over flows, then you'll want to increase the size of the stack by adding an additional option like -Xss8m.

For this problem, the jvm options of something like -Xms2g -Xmx6g -Xss8m would be a solution.

I'm sharing this information as my google searches on how to increase jvm memory took me to this solution, and the solutions didn't work with high amounts of memory allocation. Once I figured out what the specific settings were for, I was able to google how to increase the stack size and found the missing param. :) Hope this saves others time, as it would of saved me a ton of time. :)

Answer 2

This only works with 64 bit version of Java. Go to Control Panel and click on the Java icon. On the small window of Java Control Panel, click on the Java menu bar and then click on view button.

If you have two Java platforms, disable the previous version of Java, then click on Runtime parameters text field and write -Xmx1024m or less than RAM size. Don't increase heap size equal to RAM otherwise your system will crash.

Answer 3

java -d64 -Xms512m -Xmx4g HelloWorld

where, -d64: Will enable 64-bit JVM -Xms512m: Will set initial heap size as 512 MB -Xmx4g: Will set maximum heap size as 4 GB (here java file name is : HelloWorld.java)

Answer 4

On a 32-bit JVM, the largest heap size you can theoretically set is 4gb. To use a larger heap size, you need to use a 64-bit JVM. Try the following:

java -Xmx6144M -d64

The -d64 flag is important as this tells the JVM to run in 64-bit mode.

Answer 5

Yes. You Can.

You can increase your heap memory to 75% of physical memory (6 GB Heap) or higher.

Since You are using 64bit you can increase your heap size to your desired amount. In Case you are using 32bit it is limited to 4GB.

$ java -Xms512m -Xmx6144m JavaApplication

Sets you with initial heap size to 512mb and maximum heapsize to 6GB.

Hope it Helps.. :)

Answer 6

Please use below command to change heap size to 6GB

export JAVA_OPTS="-Xms6144m -Xmx6144m -XX:NewSize=256m -XX:MaxNewSize=356m -XX:PermSize=256m -XX:MaxPermSize=356m"