我们来看下面的一个例子，演示如何改变线程的优先级。高优先级线程优先执行。但是不能完全保证，因为线程是高度依赖系统的。它只提高了优先级较高的线程在低优先级线程之前执行的机会。

using system;
using system.threading;
public class mythread
{
    public void thread1()
    {
        for(int i=0; i<3; i++)
        {
            thread t = thread.currentthread;
            console.writeline(t.name + " is running");
        }


    }
}
public class threadexample
{
    public static void main()
    {
        mythread mt = new mythread();
        thread t1 = new thread(new threadstart(mt.thread1));
        thread t2 = new thread(new threadstart(mt.thread1));
        thread t3 = new thread(new threadstart(mt.thread1));
        t1.name = "highest-thread ";
        t2.name = "normal-thread ";
        t3.name = "lowest-thread ";
        t1.priority = threadpriority.highest;
        t2.priority = threadpriority.normal;
        t3.priority = threadpriority.lowest;

        t1.start();
        t2.start();
        t3.start();
    }
}

输出是不可预测的，因为线程系统依赖性高。它可以遵循任何算法抢先或非抢占式来执行。

执行上面示例代码，得到以下结果 -

highest-thread  is running
normal-thread  is running
normal-thread  is running
normal-thread  is running
lowest-thread  is running
lowest-thread  is running
lowest-thread  is running
highest-thread  is running
highest-thread  is running