Question

I wrote a java program to test the capabilities of processors by running an amount of calculations and then matching it up against my friends computers.

However when I run the program, it doesn’t use 100% of the processor. The processing power goes from 1-2% to 27% and the RAM stays at 34%.

Is this just the way java or processors work? or is it something with my code? Here’s the class that handles the calculation(Note: I’m still learning how to program, and I’m interested in the way the software interacts with the hardware):

import javax.swing.JTextPane;

public class Main {

    static int numberToCalculate = 100;
    static int otherNumberToCalculate = 50;
    static String typeOfCalculation = "all";
    static int calculated;
    static int calculations = 10000000;

    public static void calculate(JTextPane j, JTextPane j2) {
        long time = System.currentTimeMillis();
        for(int i = 0; i <= calculations; i++) {

            switch(typeOfCalculation) {
            case "Divide":
                calculated = numberToCalculate / otherNumberToCalculate;
                break;

            case "Multiply":
                calculated = numberToCalculate * otherNumberToCalculate;
                break;

            case "Plus":
                calculated = numberToCalculate + otherNumberToCalculate;
                break;

            case "Minus":
                calculated = numberToCalculate - otherNumberToCalculate;
                break;

            case "All":
                calculated = numberToCalculate / otherNumberToCalculate;
                calculated = calculated * otherNumberToCalculate;
                calculated = calculated + otherNumberToCalculate;
                calculated = calculated - otherNumberToCalculate;
                break;

            default:
                Test.UpdateText(j, "Error, please pick type of calculation.");
                Test.UpdateText(j2, "Error, please pick type of calculation.");
                break;
            }
            if(i == calculations) {
                Test.UpdateText(j, "Milliseconds: " + (System.currentTimeMillis() - time));
                Test.UpdateText(j2, "Result: " + calculated);
            }
        }
    }

    public static void main(String [] args)
    {
        Test.window();
    }

}

And here’s a picture of the output: https://i.stack.imgur.com/lH1VA.png

Answer 1

If you’re on a multi-processor machine, you’re only going to be maxing out one processor with this code. I’m going to go out on a limb and guess that you have 4 processors (or 2 with hyperthreading). That would explain why you’re only getting 27% utilization.

You’ll need to spin up extra threads doing calculations as well if you want to truly max out all of the cores in your system.