Java通过Fork/Join来优化并行计算详解编程语言

package Threads; 
 
import java.util.concurrent.ForkJoinPool; 
import java.util.concurrent.RecursiveAction; 
 
/** 
 * Created by Frank 
 */ 
public class RecursiveActionDemo extends RecursiveAction { 
 
    static int[] raw = {19, 3, 0, -1, 57, 24, 65, Integer.MAX_VALUE, 42, 0, 3, 5}; 
    static int[] sorted = null; 
    int[] source; 
    int[] dest; 
    int length; 
    int start; 
    final static int THRESHOLD = 4; 
 
    public static void main(String[] args) { 
        sorted = new int[raw.length]; 
 
        ForkJoinPool pool = new ForkJoinPool(); 
        pool.invoke(new RecursiveActionDemo(raw, 0, raw.length, sorted)); 
 
        System.out.println('['); 
        for (int i : sorted) { 
            System.out.println(i + ","); 
        } 
        System.out.println(']'); 
    } 
 
    public RecursiveActionDemo(int[] source, int start, int length, int[] dest) { 
        this.source = source; 
        this.dest = dest; 
        this.length = length; 
        this.start = start; 
    } 
 
    @Override 
    protected void compute() { 
        System.out.println("ForkJoinDemo.compute()"); 
        if (length < THRESHOLD) {    // 直接计算 
            for (int i = start; i < start + length; i++) { 
                dest[i] = source[i] * source[i]; 
            } 
        } else { // 分而治之 
            int split = length / 2; 
            /** 
             * invokeAll反复调用fork和join直到完成。 
             */ 
            invokeAll(new RecursiveActionDemo(source, start, split, dest), new RecursiveActionDemo(source, start + split, length - split, dest)); 
        } 
    } 
}