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))

, and

lock
("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