多线程总结篇一多线程的优先级

、为什么我设置了多线程的优先级，可是线程的输出并不是按优先级的高低输出啊？

    看如下代码：

View Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace _05线程的优先级
{
    class Program
    {
        static void Main(string[] args)
        {
            Thread[]t = new Thread[5];

            t[0] =new Thread( new ThreadStart(Tell));
            t[0].Name = "Lowest";
            t[0].Priority = ThreadPriority.Lowest;

            t[1] = new Thread(new ThreadStart(Tell));
            t[1].Name = "BelowNormal";
            t[1].Priority = ThreadPriority.BelowNormal;

            t[2] = new Thread(new ThreadStart(Tell));
            t[2].Name = "Normal";

            t[3] = new Thread(new ThreadStart(Tell));
            t[3].Name = "AboveNormal";
            t[3].Priority = ThreadPriority.AboveNormal;

            t[4] = new Thread(new ThreadStart(Tell));
            t[4].Name = "Highest";
            t[4].Priority = ThreadPriority.Highest;

            foreach (Thread itemt in t)
            {
                itemt.Start();
            }
            Console.ReadLine();
        }
        public static void Tell()
        {
            Console.WriteLine("当前线程为：{0},线程级别是{1}",Thread.CurrentThread.Name,Thread.CurrentThread.Priority);
        }
    }
}

　　运行结果之一：

首先，解释一下线程的优先级：

线程的优先级并不是你想象的先执行哪个后执行哪个
而是所有的线程不论优先级高低都会执行,
优先级越高表示CPU分配给该线程的时间片越多,执行时间就多
优先级越低表示CPU分配给该线程的时间片越少,执行时间就少

就这个问题我们可以做一些测试,看如下代码：

View Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace _05线程的优先级_测试线程优先级发生概率
{
    class Program
    {
        static void Main(string[] args)
        {
            Thread th1 = new Thread(delegate()
                {
                    for (int i = 0; i < 100; i++)
                    {
                        Console.Write("H");
                    }
                });
         //   th1.Priority = ThreadPriority.Highest;

            Thread th2 = new Thread(delegate()
                {
                    for (int i = 0; i < 100; i++)
                    {
                        Console.Write("A");
                    }
                }
                );
         //   th2.Priority = ThreadPriority.AboveNormal;

            Thread th3 = new Thread(delegate()
                {
                    for (int i = 0; i < 100; i++)
                    {
                        Console.Write("N");
                    }
                }
                );
          //  th3.Priority = ThreadPriority.Normal;

            Thread th4 = new Thread(delegate()
                {
                    for (int i = 0; i < 100; i++)
                    {
                        Console.Write("B");
                    }
                }
                );
         //   th4.Priority = ThreadPriority.BelowNormal;

            Thread th5 = new Thread(delegate()
                {
                    for (int i = 0; i < 100; i++)
                    {
                        Console.Write("L");
                    }
                }
                );
         //   th5.Priority = ThreadPriority.Lowest;

            th1.Start(); th2.Start(); th3.Start(); th4.Start(); th5.Start();

            Console.ReadKey();
        }
    }
}

   运行结果之一：

   

将注释代码取消注释，运行结果之一：

总结一句话就是：我们给线程分配优先级增加或减少的是该线程被优先执行的概率：