同步对象:Monitor

using System;
using System.Threading;

public class Cell
{
    int cellContents;
    bool readerFlag = false;
    public int ReadFromCell()
    {
        lock (this)
        {
            if (!readerFlag)
            {
                try
                {
                    Monitor.Wait(this);
                }
                catch (SynchronizationLockException e)
                {
                    Console.WriteLine(e);
                }
                catch (ThreadInterruptedException e)
                {
                    Console.WriteLine(e);
                }
            }
            Console.WriteLine("Consume: {0}", cellContents);
            readerFlag = false;
            Monitor.Pulse(this);
        }
        return cellContents;
    }

    public void WriteToCell(int n)
    {
        lock (this)
        {
            if (readerFlag)
            {
                try
                {
                    Monitor.Wait(this);
                }
                catch (SynchronizationLockException e)
                {
                    Console.WriteLine(e);
                }
                catch (ThreadInterruptedException e)
                {
                    Console.WriteLine(e);
                }
            }
            cellContents = n;
            Console.WriteLine("Produce: {0}", cellContents);
            readerFlag = true;
            Monitor.Pulse(this);
        }
    }
}

public class CellProd
{
    Cell cell;
    int quantity = 1;
    public CellProd(Cell box, int request)
    {

        cell = box;
        quantity = request;
    }
    public void ThreadRun()
    {
        for (int looper = 1; looper <= quantity; looper++)
            cell.WriteToCell(looper);
    }
}
public class CellCons
{
    Cell cell;
    int quantity = 1;

    public CellCons(Cell box, int request)
    {
        cell = box;
        quantity = request;
    }
    public void ThreadRun()
    {
        int valReturned;
        for (int looper = 1; looper <= quantity; looper++)
            valReturned = cell.ReadFromCell();
    }
}

public class MonitorSample
{
    public static void Main(string[] args)
    {
        int result = 0;
        Cell cell = new Cell();
        CellProd prod = new CellProd(cell, 20);
        CellCons cons = new CellCons(cell, 20);
        Thread producer = new Thread(new ThreadStart(prod.ThreadRun));
        Thread consumer = new Thread(new ThreadStart(cons.ThreadRun));
        try
        {
            producer.Start();
            consumer.Start();
            producer.Join();
            consumer.Join();
            Console.ReadLine();
        }
        catch (ThreadStateException e)
        {
            Console.WriteLine(e);
            result = 1;
        }
        catch (ThreadInterruptedException e)
        {
            Console.WriteLine(e);
            result = 1;
        }
        Environment.ExitCode = result;
    }
}