线程优先级

线程优先级

• Java提供一个线程调度器来监控程序中启动后进入就绪状态的所有线程，线程调度器按照优先级决定应该调度哪个线程来执行
• 线程的优先级用数字表示，范围从1~10
  • Thread.MIN_PRIORITY = 1;
  • Thread.MAX_PRIORITY = 10;
  • Thread.NORM_PRIORITY = 5;
• 使用以下方式改变或获取优先级
  • getPriority().setPriority(int xxx)

优先级的设定建议在start()调度前

优先级低只是意味着获得调度的概率低，这并不代表优先级低就不会被调用。这都看CPU的调度

//测试线程优先级
public class TestPriority implements Runnable{
    public static void main(String[] args) {
        //先输出主线程优先级
        System.out.println(Thread.currentThread().getName()+"--->"+Thread.currentThread().getPriority());
        Thread thread1 = new Thread(new TestPriority());
        Thread thread2 = new Thread(new TestPriority());
        Thread thread3 = new Thread(new TestPriority());
        Thread thread4 = new Thread(new TestPriority());

        //先设置优先级再启动
        new Thread(thread1).start();

        thread2.setPriority(Thread.MAX_PRIORITY);
        thread2.start();

        thread3.setPriority(1);
        thread3.start();

        thread4.setPriority(8);
        thread4.start();

    }

    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName()+"--->"+Thread.currentThread().getPriority());
    }
}