一分钟带你了解下java中的fork/join

https://zhuanlan.zhihu.com/p/97258195

 

作者对fork、join框架介绍得清楚；例子举得也很好，核心类都是用到了。

重要的2个类图：

 

 

 

 

配置上对应的代码

public class CountTask extends RecursiveTask<Integer> {
    //阀值
    private static final int THRESHOLD = 2;
    private int start;
    private int end;

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

    /**
     * The main computation performed by this task.
     *
     * @return the result of the computation
     */
    @Override
    protected Integer compute() {
        int sum = 0;
        //判断是否是拆分完毕
        int lenth = end - start;
        if (lenth <= THRESHOLD) {
            //如果拆分完毕就相加
            for (int i = start; i <= end; i++) {
                sum += i;
            }
        } else {
            //没有拆分完毕就开始拆分
            int middle = (start + end) / 2;
            CountTask leftTask = new CountTask(start, middle);
            CountTask rightTask = new CountTask(middle + 1, end);
            //执行子任务
            invokeAll(leftTask, rightTask);
            //等待子任务执行完，并得到其结果
            Integer rightResult = rightTask.join();
            Integer leftResult = leftTask.join();
            //合并子任务
            sum = leftResult + rightResult;
        }
        return sum;
    }

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ForkJoinPool forkJoinPool = new ForkJoinPool();
        CountTask countTask = new CountTask(1, 100);
        ForkJoinTask<Integer> forkJoinTask = forkJoinPool.submit(countTask);
        System.out.println(forkJoinTask.get());
    }
}