Java thread.yield（）奇怪的行为

Question

  class MyThread extends Thread{
    public void run(){
        for (int i = 0; i<=10; i++){
            System.out.println("Child Thread");
            Thread.yield();
            
        }
    }
}
  public class TestYield {
    public static void main(String[] args) {
        MyThread obj = new MyThread();
        obj.start();
        for (int i = 0; i<=10; i++){
            System.out.println("Main Thread");
        }
    }
}

Main Thread
Main Thread
Main Thread

Main Thread
Main Thread
Main Thread
Child Thread

Main Thread
Main Thread
Main Thread
Main Thread
Main Thread
Main Thread
Main Thread
Main Thread
Main Thread
Main Thread
Main Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread

所以我更新了代码，添加了行thread.sleep((long)0.1)；所做的是将主线程置于Hibernate状态一段时间，因此jvm可以获得一些时间来创建一个新线程。我正在得到我的预期输出

Main Thread
Main Thread
Main Thread
Child Thread
Main Thread
Main Thread
Main Thread
Main Thread
Main Thread
Main Thread
Main Thread
Main Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread
Child Thread

Answer 1

1-主线程太快了，以至于子线程还没有启动（或启动完）-可能main中的yield最终会帮助子线程获得运行的机会。（并从10增加到100或更多次迭代）

2-yield不保证另一个线程将运行（文档中：“The scheduler is free to ignore this hint”）_{由于在main}中没有yield,因此不太相关

3-检查java.util.concurrent.locks包。
^{实际上，yield文档还声明“使用此方法很少合适。”}