Java Stack Allocation Vs Heap Allocation of primitive/object example/test/PoC

README.md

Heap Allocation

jbang run https://gist.github.com/misTrasteos/e616b87452b215db116448216da59636\#file-stackorheapallocation-java

You will get a java.lang.OutOfMemoryError: Java heap space. As we are using no-op Epsilon GC and we are allocation plenty of Integer objects in the heap.

Stack Allocation

jbang run -D=PRIMITIVE https://gist.github.com/misTrasteos/e616b87452b215db116448216da59636\#file-stackorheapallocation-java

It will run forever as primitive ints are being created inside the stack and removed after method exit.

StackOrHeapAllocation.java

///usr/bin/env jbang "$0" "$@" ; exit $?

//JAVA_OPTIONS -Xms2m -Xmx2m
//JAVA_OPTIONS -Xlog:gc*
//JAVA_OPTIONS -XX:+UnlockExperimentalVMOptions -XX:+UseEpsilonGC
//JAVA_OPTIONS -XX:+HeapDumpOnOutOfMemoryError

public class StackOrHeapAllocation {

    public static void main(String... args) {

        Integer integerObject = null;
        int integerPrimitive = -1;

        boolean runWithPrimitives = System.getProperty("PRIMITIVE") != null;

        while(args.length > -1) // something that returns always true
            if(runWithPrimitives)
                integerPrimitive = getIntegerPrimitive();
            else
                integerObject = getIntegerObject();

        System.out.println( integerPrimitive );
        System.out.println( integerObject );
    }
    
    private static Integer getIntegerObject(){
        Integer integer = new Integer(0);
        
        return integer;
    }

    private static int getIntegerPrimitive(){
        int integer = 0;
        
        return integer;
    }

}