Why a sawtooth shaped graph?

When I run the below mentioned code using NetBeans, the allocated heap size graph resembles a sawtooth shape. I am attaching the screen capture from JVisualVM which shows the heap allocation graph in with a sawtooth shape. The program is a simple infinite loop printing "Hello, World!" into the console.

public class HelloWorld {
    public static void main(String a[]){
        while(true) {
            System.out.println("Hello, World!");
        }
    }
}

enter image description here Can anyone explain the reason behind the shape of the graph of used heap?

PS: This happens even if I run it without using NetBeans, so it is most likely not related to NetBeans...

Edit Report

1 Answer

There's lots of places it could be coming from, and it's likely implementation dependent. At least the following are possible (but are all merely speculation)

somewhere in the stack of streams underneath System.out.println there is a byte array allocation (given that one of the basic methods of an output stream is write(bytes []b, int off, int len))
it's overhead used by the monitoring software you're using (I've not used it)
it's overhead in the netbeans VM where it ends up showing the output

answered 2011-08-28T07:23:26.647

Why a sawtooth shaped graph?

1 Answer

Your Answer