I have one problem with java heap memory. I developed one client server application in java which is run as a windows service it requires more than 512MB of memory. I have 2GB of RAM but when I run my application it throws an exception
Out of memory error:java heap space
but I have already set heap size (maximum 512MB) in the java control panel and I still get the same error. I can't set heap size through the command line because my application runs as a windows service so how can I increase the default heap size?
The Java Virtual Machine takes two command line arguments which set the initial and maximum heap sizes: -Xms and -Xmx. You can add a system environment variable named _JAVA_OPTIONS, and set the heap size values there.
For example if you want a 512Mb initial and 1024Mb maximum heap size you could use:
under Windows:
SET _JAVA_OPTIONS = -Xms512m -Xmx1024m
under Linux:
export _JAVA_OPTIONS="-Xms512m -Xmx1024m"
It is possible to read the default JVM heap size programmatically by using totalMemory() method of Runtime class. Use following code to read JVM heap size.
public class GetHeapSize {
public static void main(String[]args){
//Get the jvm heap size.
long heapSize = Runtime.getRuntime().totalMemory();
//Print the jvm heap size.
System.out.println("Heap Size = " + heapSize);
}
}