在组级别而不是应用程序级别处理并发

将内容添加到并发字典是一个非常快速的操作。您也没有让线程等待第一个线程完成,如果它们无法获得锁,您将立即丢弃。

这让我觉得 Double Checked Lock

所以,我只需要做你的内部检查,不需要外部检查:

if(dict.TryAdd(groupId, "Added") == false) 
{
        throw new Exception("request already accepted");
}

will not lock

另一个有趣的话题是如何清理这个。

// NOTE: THIS IS JUST PSEUDOCODE

// In your controller, you can simply do this...
//
public SomeController()
{

    using (var operation = new GroupOperation(groupId)) 
    {
        // In here I am sure I am the only operation of this group
    } 

    // In here I am sure that the operation got removed from the dictionary

}


// This class hides all the complexity of the concurrent dictionary
//
public class GroupOperation : IDisposable
{
    var singletonDictionary = new ConcurrentDictionary<int,int>()
    int GroupId;

    public GroupOperation(int GroupID)
    {
         this.GroupId = GroupId;
         if(!singletonDictionary.TryADd(GroupID, 1))
         {
             throw new Exception("Sorry, operation in progress for your group");
         }
    }

    protected virtual void Dispose(bool disposing)
    {
       singletonDictionary.Remove(GroupId)
    }
}