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

You can increase the Heap Size by passing JVM parameters -Xms and -Xmx like below:

For Jar Files:

java -jar -Xms4096M -Xmx6144M jarFilePath.jar

For Java Files:

 java -Xms4096M -Xmx6144M ClassName

The above parameters increase the InitialHeapSize (-Xms) to 4GB (4096 MB) and MaxHeapSize(-Xmx) to 6GB (6144 MB).

But, the Young Generation Heap Size will remain same and the additional HeapSize will be added to the Old Generation Heap Size. To equalize the size of Young Gen Heap and Old Gen Heap, use -XX:NewRatio=1 -XX:-UseAdaptiveSizePolicy params.

java -jar -Xms4096M -Xmx6144M -XX:NewRatio=1 -XX:-UseAdaptiveSizePolicy pathToJarFile.jar

-XX:NewRatio = Old Gen Heap Size : Young Gen HeapSize (You can play with this ratio to get your desired ratio).