Lock锁机制在线程中的应用

（一）锁的概念

（二）lock关键词在C#语言中的用法

代码class Program
{
    private static readonly object _syncRoot = new Object();
    static Thread t1 = new Thread(new ParameterizedThreadStart(P));
    static Thread t2 = new Thread(new ParameterizedThreadStart(P));
    static Thread t3 = new Thread(new ParameterizedThreadStart(P));
    static void Main(string[] args)
    {
        t1.Name = "A";
        t2.Name = "B";
        t3.Name = "C";

        t1.Start(t1);
        t2.Start(t2);
        t3.Start(t3);
        //t1.Join();
        //t2.Join();
        //t3.Join();
        //Console.WriteLine("------------");
        //Console.ReadKey();
    }

    static void P(object name)
    {
        Thread t = name as Thread;
        Console.WriteLine("线程名:{0}-1 占用资源\t时间:{5:HH:mm:ss.fff}  当前线程:{1,-18} A:{2,-18} B:{3,-18} C:{4}",
            t.Name, t.ThreadState.ToString() + " ID:" + t.ManagedThreadId, t1.ThreadState.ToString() + " ID:" + t1.ManagedThreadId,
            t2.ThreadState.ToString() + " ID:" + t2.ManagedThreadId, t3.ThreadState.ToString() + " ID:" + t3.ManagedThreadId,
            DateTime.Now);
        lock (_syncRoot)
        {
            Console.WriteLine("线程名:{0}-2 Sleep前\t时间:{5:HH:mm:ss.fff}  当前线程:{1,-18} A:{2,-18} B:{3,-18} C:{4}",
                t.Name, t.ThreadState.ToString() + " ID:" + t.ManagedThreadId, t1.ThreadState.ToString() + " ID:" + t1.ManagedThreadId,
                t2.ThreadState.ToString() + " ID:" + t2.ManagedThreadId, t3.ThreadState.ToString() + " ID:" + t3.ManagedThreadId,
                DateTime.Now);
            Thread.Sleep(5000);
            Console.WriteLine("线程名:{0}-3 Sleep后\t时间:{5:HH:mm:ss.fff}  当前线程:{1,-18} A:{2,-18} B:{3,-18} C:{4}",
                t.Name, t.ThreadState.ToString() + " ID:" + t.ManagedThreadId, t1.ThreadState.ToString() + " ID:" + t1.ManagedThreadId,
                t2.ThreadState.ToString() + " ID:" + t2.ManagedThreadId, t3.ThreadState.ToString() + " ID:" + t3.ManagedThreadId,
                DateTime.Now);
        }
        Console.WriteLine("线程名:{0}-4 释放资源\t时间:{5:HH:mm:ss.fff}  当前线程:{1,-18} A:{2,-18} B:{3,-18} C:{4}",
            t.Name, t.ThreadState.ToString() + " ID:" + t.ManagedThreadId, t1.ThreadState.ToString() + " ID:" + t1.ManagedThreadId,
            t2.ThreadState.ToString() + " ID:" + t2.ManagedThreadId, t3.ThreadState.ToString() + " ID:" + t3.ManagedThreadId,
            DateTime.Now);
    }
}

代码执行分析如下：下图列出了代码四次执行输出的结果。