主程序Program.cs

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

namespace MultiThreadedPrinting
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("********Synchronizing Threads*************");
            Printer p = new Printer();
            Thread[] threads = new Thread[10];
            for (int i = 0; i < 10; i++)
            {
                threads[i] = new Thread(new ThreadStart(p.PrintNumber));
                threads[i].Name = string.Format("Worker thread #{0}", i);
            }

foreach (Thread t in threads)
                t.Start();
            Console.ReadLine();
        }
    }
}

类Printer.cs

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

namespace MultiThreadedPrinting
{
    public class Printer
    {
        public void PrintNumber()
        {
                 Console.WriteLine("-> {0} is executing PrintNumbers()", Thread.CurrentThread.Name);
                for (int i = 0; i < 10; i++)
                {
                    Random r = new Random();
                    Thread.Sleep(1000 * r.Next(5));
                    Console.Write(i + ",");
                }
                Console.WriteLine();

}

}
}

运行程序你会发现出现意想不到的结果，一些线程可能被挂起，出现了并发的问题。

为了解决并发问题C#提供了特别的关键字：Lock

PrintNumber()
中修改为

lock (this)
            {
                Console.WriteLine("-> {0} is executing PrintNumbers()", Thread.CurrentThread.Name);
                for (int i = 0; i < 10; i++)
                {
                    Random r = new Random();
                    Thread.Sleep(1000 * r.Next(5));
                    Console.Write(i + ",");
                }
                Console.WriteLine();
            }