Java Parallel Sort

Java 8 introduced .parallelSort() to the Array class. It uses multiple threads to perform the sort operation and is therefore quicker. Here’s some code to benchmark .parallelSort() against the regular .sort():

    var numbers = new Random().ints(90000000, 1, 999999999);
    int[] arrNumbers = numbers.toArray();
    //List<Integer> lstNumbers = numbers.boxed().collect(Collectors.toList());

    Date dtStart, dtEnd;
    long diffInMillis = -1;
    dtStart = new Date();

    //Comment out the one to execute
    //Arrays.sort(arrNumbers);  //Takes ~6 seconds
    //Arrays.parallelSort(arrNumbers);  //Takes ~1 second

    dtEnd = new Date();
    diffInMillis = dtEnd.getTime() - dtStart.getTime();
    System.out.print("Execution time: ");
    System.out.println(diffInMillis);

With the above code, we get an execution time of 6 seconds for the .sort() execution and 1 second for the .parallelSort() execution on OpenJDK 17 running on an M1 Pro CPU.