Java并发编程--fork-join framework(a parallelizable algorithm)

数组归并排序代码实现（ForkJoin版）:
/**
 *
 */
package concurrent.forkjoin;
import java.util.Arrays;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveAction;
import algorithm.sort.MergeSortAlgorithm;
/**
 * A merge sort demonstration algorithm with the fork-join framework(a parallelizable algorithm)
 *
 * 数组归并排序: http://blog.csdn.net/yang_net/archive/2010/08/01/5781012.aspx
 *
 * @author yangwm Aug 12, 2010 11:15:47 AM
 */
public class MergeSortForkJoin extends RecursiveAction {
    /**
     *
     */
    private static final long serialVersionUID = -7490351302704617127L;
   
    private static final int THRESHOLD = 4;
    private final int[] number;
    private int[] result;
   
    public MergeSortForkJoin(int[] number) {
        this.number = number;
    }
    @Override
    protected void compute() {
        if (number.length <= THRESHOLD) {
            result = MergeSortAlgorithm.mergeSort(number);
        } else {
            int middle = number.length / 2;
            /*
             * Partition the list into two lists and sort them recursively
             */
            int left[] = new int[middle];
            for (int i = 0; i < middle; i++) {
                left[i] = number[i];
            }
            int right[] = new int[number.length - middle];
            for (int i = 0; i < number.length - middle; i++) {
                right[i] = number[middle + i];
            }
            /*
             * Merge the two sorted lists
             */
            MergeSortForkJoin leftForkJoin = new MergeSortForkJoin(left);
            MergeSortForkJoin rightForkJoin = new MergeSortForkJoin(right);
            invokeAll(leftForkJoin, rightForkJoin); // coInvoke(leftForkJoin, rightForkJoin);
            result = MergeSortAlgorithm.merge(leftForkJoin.result, rightForkJoin.result);
        }
    }
    public int[] merge(int left[], int right[]) {
        int[] result = new int[left.length + right.length];
        int leftPos = 0;
        int rightPos = 0;
        int resultPos = 0;
        while (leftPos < left.length && rightPos < right.length) {
            /* Merge sorted sublists */
            if (left[leftPos] <= right[rightPos]) {
                result[resultPos++] = left[leftPos++];
            } else {
                result[resultPos++] = right[rightPos++];
            }
        }
        if (leftPos < left.length) {
            /* append left to result */
            while (leftPos < left.length) {
                result[resultPos++] = left[leftPos++];
            }
        } else {
            /* append right to result */
            while (rightPos < right.length) {
                result[resultPos++] = right[rightPos++];
            }
        }
        return result;
    }
    public static void main(String[] args) {
        int[] number = { 4, 2, 1, 2, 7, 3, 9, 0, 0, 11, 10, 6, 15, 8 };
        MergeSortForkJoin mergeSortForkJoin = new MergeSortForkJoin(number);
        ForkJoinPool forkJoinPool = new ForkJoinPool();
        forkJoinPool.invoke(mergeSortForkJoin);
        System.out.println(Arrays.toString(mergeSortForkJoin.result));
    }
}
 

输出：
[0, 0, 1, 2, 2, 3, 4, 6, 7, 8, 9, 10, 11, 15]

学习参考资料：
Stick a fork in it, Part I & Stick a fork in it, Part II : http://www.briangoetz.com/pubs.html
A Java ForkJoin Framework: http://gee.cs.oswego.edu/dl/papers/fj.pdf
JDK 7 中的 Fork/Join 模式 : http://www.ibm.com/developerworks/cn/java/j-lo-forkjoin/
RecursiveAction (Java Platform SE 7) : http://download.java.net/jdk7/docs/api/java/util/concurrent/RecursiveAction.html