Java多线程高并发中的Fork/Join框架机制详解

package test.forkjoin;
 
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.ForkJoinTask;
import java.util.concurrent.RecursiveTask;
 
/**
 *
 */
class MyTask extends RecursiveTask<Integer> {
    //拆分差值不能超过10，每次计算10以内的连加操作
    private static final Integer NUMBER = 10;
    private int begin; //拆分左区间的值
    private int end; //拆分右区间的值
    private int result; //最终结果
 
    public MyTask(int begin,int end) {
        this.begin = begin;
        this.end = end;
    }
 
    @Override
    protected Integer compute() {
        //判断区间差值是否大于10
        if ((end - begin) <= NUMBER) {
            //将区间内的值依次相加
            for (int i = begin; i <= end; i++) {
                result += i;
            }
        } else { //区间差值大于10，进一步拆分
            //获取中间值
            int middle = (begin + end) / 2;
            //拆分的左区间
            MyTask taskLeft = new MyTask(begin,middle);
            //拆分的右区间
            MyTask taskRight = new MyTask(middle + 1,end);
            //fork方法进行拆分
            taskLeft.fork();
            taskRight.fork();
            //join方法进行合并
            result = taskLeft.join() + taskRight.join();
        }
        return result;
    }
}
 
public class ForkJoinDemo {
    public static void main(String[] args) {
        //创建MyTask对象
        MyTask myTask = new MyTask(1,100);
        //创建分支合并池对象
        ForkJoinPool forkJoinPool = new ForkJoinPool();
        ForkJoinTask<Integer> forkJoinTask = forkJoinPool.submit(myTask);
        try {
            //获取最终合并后的结果
            Integer ans = forkJoinTask.get();
            System.out.println(ans);
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            //关闭池对象
            forkJoinPool.shutdown();
        }
    }
}