C# 应用程序在关机时不退出（有时）

Question

我的应用程序可以防止窗口关闭，但仅限于某些计算机，而不是始终如此。调试起来有点棘手。 我认为这是由于我的 TCP 服务器造成的。它是一个异步服务器，我的应用程序处理 CloseReason == WindowsShutDown。 发生这种情况时，我的应用程序仍然作为进程运行，但无法从任务栏/系统托盘访问。

我想知道是否有人能看到我的服务器代码有任何明显的问题。

下面是我的服务器的代码。 Stop() 方法是从主窗体 Close() 事件中调用的。

public class MantraServer
    {
        protected int portNumber;
        private bool ShuttingDown = false;

        //the main socket the server listens to
        Socket listener;

        //Constructor - Start a server on the given IP/port
        public MantraServer(int port, IPAddress IP)
        {
            this.portNumber = port;
            Start(IP);
        }

        /// 
        /// Description: Start the threads to listen to the port and process
        /// messages.
        ///
        public void Start(IPAddress IP)
        {
            try
            {
                //We are using TCP sockets
                listener = new Socket(AddressFamily.InterNetwork,
                                          SocketType.Stream,
                                          ProtocolType.Tcp);

                //Assign the any IP of the machine and listen on port number 3000
                IPEndPoint ipEndPoint = new IPEndPoint(IP, 3000);

                //Bind and listen on the given address
                listener.Bind(ipEndPoint);
                listener.Listen(10);

                //Accept the incoming clients
                listener.BeginAccept(new AsyncCallback(OnAccept), listener);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "MANTRA Network Start Error",
                    MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        /// Decription: Stop the threads for the port listener.
        public bool Stop()
        {
            try
            {
                ShuttingDown = true;
                listener.Shutdown(SocketShutdown.Both);
                listener.Close();
                listener = null;
                System.Threading.Thread.Sleep(500); //wait for half second while the server closes
                return true;
            }
            catch (Exception)
            {
                return false;
            }
        }

        /// 
        /// Decription: Call back method to accept new connections.
        /// <param name="ar">Status of an asynchronous operation.</param>
        private void OnAccept(IAsyncResult ar)
        {
            try
            {
                if (!ShuttingDown)
                {
                    MantraStatusMessage InMsg = new MantraStatusMessage();
                    InMsg.Socket = ((Socket)ar.AsyncState).EndAccept(ar);
                    //Start listening for more clients
                    listener.BeginAccept(new AsyncCallback(OnAccept), listener);

                    //Once the client connects then start receiving the commands from them
                    InMsg.Socket.BeginReceive(InMsg.buffer, 0, InMsg.buffer.Length, SocketFlags.None,
                        new AsyncCallback(OnReceive), InMsg);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "MANTRA Network Accept Error",
                    MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        ///  
        /// Receives the data, puts it in a buffer and checks if we need to receive again.  
        public void OnReceive(IAsyncResult result)
        {
            MantraStatusMessage InMsg = (MantraStatusMessage)result.AsyncState;
            int read = InMsg.Socket.EndReceive(result);
            if (read > 0)
            {
                for (int i = 0; i < read; i++)
                {
                    InMsg.TransmissionBuffer.Add(InMsg.buffer[i]);
                }
                //we need to read again if this is true  
                if (read == InMsg.buffer.Length)
                {
                    InMsg.Socket.BeginReceive(InMsg.buffer, 0, InMsg.buffer.Length, SocketFlags.None, OnReceive, InMsg);
                    Console.Out.WriteLine("Message Too big!");
                }
                else
                {
                    Done(InMsg);
                }
            }
            else
            {
                Done(InMsg);
            }
        }

        ///  
        /// Deserializes and outputs the received object  
        public void Done(MantraStatusMessage InMsg)
        {
            Console.Out.WriteLine("Received: " + InMsg.msg);
            MantraStatusMessage received = InMsg.DeSerialize();
            Console.WriteLine(received.msg.Message);
        }
    }

编辑

感谢Hogan，提供了有关调用 Close() 的更多信息：

发送或接收数据的请求被禁止，因为套接字未连接并且（当使用 sendto 调用在数据报套接字上发送时） ) 未提供地址。

还不完全确定这意味着什么。

Answer 1

您必须向 Windows 事件日志添加一些日志记录才能查看发生了什么。

最好的起点是返回 false 的 catch（因为这将阻止 Windows 关闭）。如果您在那里记录原因，那么至少您可以查看事件日志以了解为什么您的服务不会关闭。

Answer 2

您应该始终确保在回调发生时调用任何异步方法的 EndXXX 对应方法。您无法执行此操作：

InMsg.Socket = ((Socket)ar.AsyncState).EndAccept(ar);

因为它位于 !shuttingDown 块中。调用它...捕获错误。