fork/join 就是把大任务分成无数个小任务来进行并行计算，提高运算速度比如我们来计算从1加到10000

import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.Future;
import java.util.concurrent.RecursiveTask;

/**
 * Created by qiuyunjie on 2018/5/9.
 */
public class ForkJoinTaskExample extends RecursiveTask<Integer> {

    public static final int threshold = 2;
    private int start;
    private int end;

    public ForkJoinTaskExample(int start, int end) {
        this.start = start;
        this.end = end;
    }

    @Override
    protected Integer compute() {
        int sum = 0;

        //如果任务足够小就计算任务
        boolean canCompute = (end - start) <= threshold;
        if (canCompute) {
            for (int i = start; i <= end; i++) {
                sum += i;
            }
        } else {
            // 如果任务大于阈值，就分裂成两个子任务计算
            System.err.println("=====任务分解======");
            int middle = (start + end) / 2;
            ForkJoinTaskExample leftTask = new ForkJoinTaskExample(start, middle);
            ForkJoinTaskExample rightTask = new ForkJoinTaskExample(middle + 1, end);

            // 执行子任务
            leftTask.fork();
            rightTask.fork();

            // 等待任务执行结束合并其结果
            int leftResult = leftTask.join();
            int rightResult = rightTask.join();

            // 合并子任务
            sum = leftResult + rightResult;
        }
        return sum;
    }

    public static void main(String[] args) {
        ForkJoinPool forkjoinPool = new ForkJoinPool();

        //生成一个计算任务，计算1+2+3+4
        ForkJoinTaskExample task = new ForkJoinTaskExample(1, 10000);

        //执行一个任务
        Future<Integer> result = forkjoinPool.submit(task);

        try {
            System.out.println("result:{}" + result.get());
        } catch (Exception e) {
            System.out.println("exception" +  e);
        }
    }
}

具体原理明天再详细解析， 今天先放个小例子