c# - (无效的方法)避免在 C# 中双重检查锁

Question

这是避免双重检查锁的有效且优化的方法吗:

public class SomeBaseClass
{
     protected static object InitializeLock = new object();
     protected static bool IsInitialized = false;

     public void SomeFunction()
     {
         if (!IsInitialized)
         {
             System.Threading.Thread.MemoryBarrier();
             lock (InitializeLock)
             {
                 // do init stuff
                 IsInitialized = true;
             }
     }

     //Do stuff that have to happen when function is called
    }
}

这是经过双重检查的替代方案:

public class SomeBaseClass
{
     protected static object InitializeLock = new object();
     protected static bool IsInitialized = false;

     public void SomeFunction()
     {
         if (!IsInitialized)
         {
             lock (InitializeLock)
             {
                 if (!IsInitialized)
                 {                              
                     // do init stuff
                     IsInitialized = true;
                 }
             }
         }

     //Do stuff that have to happen when function is called
    }
}

Answer 1

不，因为线程切换可以在两个线程通过 if (!IsInitialized)

后立即发生

有一篇很棒的文章在创建单例的上下文中解释了这个主题:http://csharpindepth.com/Articles/General/Singleton.aspx (乔恩·斯基特)