ForkJoin与Stream并行流

ForkJoin 在 JDK 1.7 , 并行执行任务!提高效率。大数据量!

ForkJoin 特点:工作窃取

这个里面维护的都是双端队列

以下计算1-10_0000_0000的和，for循环与ForkJoin效率差别不大，但是使用Stream并行流效果显著！！！

import java.util.*;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveTask;
import java.util.stream.LongStream;

/**
 * 求和计算的任务!
 * // 如何使用 forkjoin
 * // 1、forkjoinPool 通过它来执行
 * // 2、计算任务 forkjoinPool.execute(ForkJoinTask task)
 * // 3. 计算类要继承 ForkJoinTask
 */
class test1{

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        test1(); // 6911
        test2(); // 7249
        test3(); // 156
    }

    // 普通程序员
    public static void test1(){
        Long sum = 0L;
        long start = System.currentTimeMillis();
        for (Long i = 1L; i <= 10_0000_0000; i++) {
            sum += i;
        }
        long end = System.currentTimeMillis();
        System.out.println("sum="+sum+" 时间:"+(end-start));
    }

    // 会使用ForkJoin
    public static void test2() throws ExecutionException, InterruptedException {
        long start = System.currentTimeMillis();
        ForkJoinPool forkJoinPool = new ForkJoinPool();
        Forkjion task = new Forkjion(0L, 10_0000_0000L);
        Forkjion submit = (Forkjion) forkJoinPool.submit(task);// 提交任务
        Long sum = submit.get();
        long end = System.currentTimeMillis();
        System.out.println("sum="+sum+" 时间:"+(end-start));
    }

    // 使用Stream并行流!效率最高
    public static void test3(){
        long start = System.currentTimeMillis();
        // Stream并行流 ()(]
        long sum = LongStream.rangeClosed(0L,
                10_0000_0000L).parallel().reduce(0, Long::sum);
        long end = System.currentTimeMillis();System.out.println("sum="+sum+"时间:"+(end-start));
    }

}

class Forkjion extends RecursiveTask {

    private Long start; // 1
    private Long end; // 1990900000
    // 临界值
    private Long temp = 10000L;
    public Forkjion(Long start, Long end) {
        this.start = start;
        this.end = end;
    }


    @Override
    protected Long compute() {
        if ((end-start)