线程优先级_priority

线程优先级_priority

• 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;
• 使用以下方法改变或获取优先级
  • getPriority().setPriority(int xxx);
• 优先级低只是意味着获得调度的概率低，并不是优先级低就不会被调用，看CPU调度
• 性能倒置：优先级低的线程较优先级高的先执行
• 优先级的设定建议在start（）调度前

测试代码：

**package multithreading;

// 测试线程的优先级
public class TestPriority {
    public static void main(String[] args) {
        // 主线程默认优先级
        System.out.println(Thread.currentThread().getName()+"——>"+Thread.currentThread().getPriority());

        MyPriority myPriority = new MyPriority();

        Thread t1 = new Thread(myPriority);
        Thread t2 = new Thread(myPriority);
        Thread t3 = new Thread(myPriority);
        Thread t4 = new Thread(myPriority);
        Thread t5 = new Thread(myPriority);
        Thread t6 = new Thread(myPriority);

        // 先设置线程优先级，再启动
        t1.start();

        t2.setPriority(1);
        t2.start();

        t3.setPriority(4);
        t3.start();

        t4.setPriority(Thread.MAX_PRIORITY);
        t4.start();

        t5.setPriority(7);
        t5.start();

        t6.setPriority(8);
        t6.start();
    }
}

class MyPriority implements Runnable{

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

**

运行结果：