C#中Lock使用

好久没有写了，前段时间写WPF的学习笔记，由于目前换公司了，所以WPF的笔记要延后写了，今天碰到一个关于LOCK的使用问题特记录下来。今天在写一个单例模式的类。

首先定义个接口给其它工程使用的方法：

  public interface ICallService : IO4PubBase

    {

        List GetFundInfo(TGetFundInfoIn paramIn);

    }

然后实现这个接口，这里用到了单例同时也用到了锁：

 public class CallService

    {

        public static ICallService GetInstance()

        {

            return JC_CallService.GetInstance();

        }

    }

    internal class JC_CallService : ICallService

    {

        private static JC_CallService _callServicce;

        private static readonly object _lock = new object();

        private static LSJC_Controller _lsjc_Controller;

        private JC_CallService()

        {

            _lsjc_Controller = LSJC_Controller.GetInstance();

        }

        public static JC_CallService GetInstance()

        {

            if (_callServicce == null)

            {

                lock (_lock)  //有人会用：typeof(JC_CallService)或者this

                {

                    if (_callServicce == null)

                    {

                        _callServicce = new JC_CallService();

                    }

                }

            }

            return _callServicce;

        }

        public List GetFundInfo(TGetFundInfoIn paramIn)

        {

            return _lsjc_Controller.GetFundInfo(paramIn);

        }

        public List GetFundInfoMulti(List paramListIn)

        {

            return _lsjc_Controller.GetFundInfoMulti(paramListIn);

        }

    }

上面肯定很多人那么写并且认为不会有问题，我以前就用过lock(this)然后发生问题了。查阅资料发现了微软的具体解释：

lock ensures that one thread does not enter a critical section of code while another thread is in the critical section. If another thread attempts to enter a locked code, it will wait, block, until the object is released.

The section Threading (C# Programming Guide) discusses threading.

lock calls Enter at the beginning of the block and Exit at the end of the block.

In general, avoid locking on a public type, or instances beyond your code's control. The common constructs lock (this), lock (typeof (MyType)), andlock ("myLock") violate this guideline:

• lock (this) is a problem if the instance can be accessed publicly.

• lock (typeof (MyType)) is a problem if MyType is publicly accessible.

• lock(“myLock”) is a problem since any other code in the process using the same string, will share the same lock.

Best practice is to define a private object to lock on, or a private static object variable to protect data common to all instances.

所以以后使用要切记！ 微软资料地址