C＃中的线程监视器类

Question

In my c# application multiple clients will access the same server, to process one client ata a time below code is written.In the code i used Moniter class and also the queue class.will this code affect the performance.if i use Monitor class, then shall i remove queue class from the code.

Sometimes my remote server machine where my application running as service is totally down.is the below code is the reasond behind, coz all the clients go in a queue, when i check the netstatus -an command using command prompt, for 8 clients it shows 50 connections are holding in Time-wait...

Below is my code where client acces the server ...

if (Id == "")
{
    System.Threading.Monitor.Enter(this);
    try
    {
        if (Request.AcceptTypes == null)
        {
            queue.Enqueue(Request.QueryString["sessionid"].Value);

            string que = "";

            que = queue.Dequeue();
            TypeController.session_id = que;
            langStr = SessionDatabase.Language;
            filter = new AllThingzFilter(SessionDatabase, parameters, langStr);
            TypeController.session_id = "";

            filter.Execute();
            Request.Clear();

            return filter.XML;
        }
        else
        {
            TypeController.session_id = "";
            filter = new AllThingzFilter(SessionDatabase, parameters, langStr);

            filter.Execute();
        }
    }
    finally
    {
        System.Threading.Monitor.Exit(this);
    }
}

Answer 1

Locking this is pretty wrong, it won't work at all if every thread uses a different instance of whatever class this code lives in. It isn't clear from the snippet if that's the case but fix that first. Create a separate object just to store the lock and make it static or give it the same scope as the shared object you are trying to protect (also not clear).

You might still have trouble since this sounds like a deadlock rather than a race. Deadlocks are pretty easy to troubleshoot with the debugger since the code got stuck and is not executing at all. Debug + Break All, then Debug + Windows + Threads. Locate the worker threads in the thread list. Double click one to select it and use Debug + Call Stack to see where it got stuck. Repeat for other threads. Look back through the stack trace to see where one of them acquired a lock and compare to other threads to see what lock they are blocking on.

That could still be tricky if the deadlock is intricate and involves multiple interleaved locks. In which case logging might help. Really hard to diagnose mandelbugs might require a rewrite that cuts back on the amount of threading.