C#的多线程锁定问题

Question

大家好，我在学习C#多线程编程时遇到了下面的问题。
我建立了三个线程，一个生产者Producer和两个消费者Consumer，在HoldIntegerSync的内部对多线程读取与写入进行同步，但是为什么我在HoldIntegerSync的get和set中的lock锁定不起作用呢？所有线程都能同时进入被lock包裹的代码。using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;namespace ConsoleApplication2
{
    public class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Main Start.");            try
            {
                HoldIntegerSync his = new HoldIntegerSync();
                Consumer consumer = new Consumer(his);
                Consumer consumerTwo = new Consumer(his);                Producer producer = new Producer(his);                Thread producerThread = new Thread(new ThreadStart(producer.Produce));
                producerThread.Name = "Producer";                Thread consumerThread1 = new Thread(new ThreadStart(consumer.Consume));
                consumerThread1.Name = "Consumer";                Thread consumerThread2 = new Thread(new ThreadStart(consumerTwo.Consume));
                consumerThread2.Name = "ConsumerTwo";                consumerThread1.Start();
                consumerThread2.Start();
                producerThread.Start();            }
            catch (Exception e)
            {
                Console.WriteLine("Catch Exception : \n" + e.ToString());                Console.WriteLine("Exception Message : \n" + e.Message);                Console.WriteLine("Exception Inner :\n" + e.InnerException);
            }            Console.WriteLine("Main End.");
        }
    }    class Producer
    {
        private Random rd = new Random(10);
        
        private HoldIntegerSync sync;
        public Producer(HoldIntegerSync his)
        {
            this.sync = his;
        }        public void Produce()
        {
            sync.Buffer = rd.Next();
        }
    }    class Consumer
    {
        private HoldIntegerSync sync;
        public Consumer(HoldIntegerSync his)
        {
            this.sync = his;
        }        public void Consume()
        {
            Console.WriteLine(Thread.CurrentThread.Name + " read: {0}", sync.Buffer);
        }
    }    class HoldIntegerSync
    {
        private int count = 0;        private int _Buffer;        public int Buffer
        {
            get
            {
                lock (this)
                {
                    Console.WriteLine(Thread.CurrentThread.Name + " Enter lock.");
                    if (count == 0)
                    {
                        Console.WriteLine(Thread.CurrentThread.Name + " waiting read.");
                        Monitor.Wait(this);
                    }                    Console.WriteLine(Thread.CurrentThread.Name + " reading:{0}", _Buffer);                    count--;                    Monitor.PulseAll(this);                    
                }                Console.WriteLine(Thread.CurrentThread.Name + " Exit lock.");                return _Buffer;
            }            set
            {
                lock (this)
                {
                    Console.WriteLine(Thread.CurrentThread.Name + " Enter lock");
                    if (count == 1)
                    {
                        Console.WriteLine(Thread.CurrentThread.Name + " waiting write.");
                        Monitor.Wait(this);
                    }                    Console.WriteLine(Thread.CurrentThread.Name + " writing:{0}", value);                    _Buffer = value;                    count++;                    Monitor.PulseAll(this);                    
                }                Console.WriteLine(Thread.CurrentThread.Name + " Exit lock.");
            }
        }
    }}

Answer 1

Monitor.Wait(object);
 释放对象上的锁并阻止当前线程，直到它重新获取该锁。

Answer 2

再详细说明一下吧lock(object)
{
    //do something
}
完全等价于下面的代码：
try
{
    Moniter.Enter(object);
    //do something
}
catch{}
finnaly
{
    Moniter.Exit(object);
}你在lock块中，使用了Monitor.Wait(object)方法，等于已暂时释放了锁，其他线程当然可以进入了