Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.util.Arrays;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveAction;

public class Main {
    public static void main(String[] args) {
        ForkJoinPool fjPool = new ForkJoinPool();
        int[] a = new int[3333344];
        for (int i = 0; i < a.length; i++) {
            int k = (int) (Math.random() * 22222);
            a[i] = k;
        }
        ForkJoinQuicksortTask forkJoinQuicksortTask = new ForkJoinQuicksortTask(a, 0, a.length - 1);
        long start = System.nanoTime();
        fjPool.invoke(forkJoinQuicksortTask);
        System.out.println("Time: " + (System.nanoTime() - start));
    }
}

class ForkJoinQuicksortTask extends RecursiveAction {
    int[] a;
    int left;
    int right;

    public ForkJoinQuicksortTask(int[] a) {
        this(a, 0, a.length - 1);
    }

    public ForkJoinQuicksortTask(int[] a, int left, int right) {
        this.a = a;
        this.left = left;
        this.right = right;
    }

    @Override
    protected void compute() {
        if (serialThresholdMet()) {
            Arrays.sort(a, left, right + 1);
        } else {
            int pivotIndex = partition(a, left, right);
            ForkJoinQuicksortTask t1 = new ForkJoinQuicksortTask(a, left, pivotIndex - 1);
            ForkJoinQuicksortTask t2 = new ForkJoinQuicksortTask(a, pivotIndex + 1, right);
            t1.fork();
            t2.compute();
            t1.join();
        }
    }

    int partition(int[] a, int p, int r) {
        int i = p - 1;
        int x = a[r];
        for (int j = p; j < r; j++) {
            if (a[j] < x) {
                i++;
                swap(a, i, j);
            }
        }
        i++;
        swap(a, i, r);
        return i;
    }

    void swap(int[] a, int p, int r) {
        int t = a[p];
        a[p] = a[r];
        a[r] = t;
    }

    private boolean serialThresholdMet() {
        return right - left < 100000000;
    }
}