[英]C# Async TCP Server overkill?
这实际上是一个实现问题,所以我觉得最好从我的具体案例开始。
我有一个C#服务器,它从移动客户端异步侦听TCP连接。 当移动客户端连接新线程启动时,客户端发送一些(通常<100字节)文本消息并接收相似大小的文本消息。 服务器响应后,它会关闭连接并结束线程。
当前的基本用法是用户登录,有时最多5分钟检查一些内容, 发送少量消息,从而快速连续地在服务器上创建新线程 ,并且几小时后它们仅断开连接。 此外,每个用户都有自己的PC上运行的服务器,因此大多数服务器在任何给定时间只能连接一个客户端,在RARE情况下只有两个。
现在我遇到了以下错误, 现有连接被远程主机强行关闭 ,它让我思考, 我做错了吗?
所以我的问题:
回答这里的一些问题:
public void StartListening()
{
//Data buffer for incoming data.
byte[] bytes = new Byte[1024];
//Establish the local endpoint for the socket.
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, Port);
//Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
listener.SetSocketOption(SocketOptionLevel.Socket,SocketOptionName.DontLinger,1);
listener.SetSocketOption(SocketOptionLevel.Socket,SocketOptionName.ReuseAddress,1);
//Bind the socket to the local endpoint and listen for
//incoming connections.
try
{
listener.Bind(localEndPoint);
listener.Listen(100);
while (listening)
{
//Set the event to nonsignaled state.
allDone.Reset();
//Start an asychronous socket to listen for connections.
Print("Waiting for a connection...");
listener.BeginAccept(
new AsyncCallback(AcceptCallback),
listener);
//Wait until a connection is made before continuing.
allDone.WaitOne();
}
}
catch (Exception e)
{
Print(e.ToString());
}
listener.Close();
}
public void AcceptCallback(IAsyncResult arg)
{
//Signal the main thread to continue.
allDone.Set();
try
{
//Get the socket that handles the client request.
Socket listener = (Socket) arg.AsyncState;
Socket handler = listener.EndAccept(arg);
//Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
catch (ObjectDisposedException ex)
{
Print("Server terminated from another thread.");
}
}
public void ReadCallback(IAsyncResult arg)
{
String content = String.Empty;
//Retrieve the state object and the handler socket
//from the asynchronous state object.
StateObject state = (StateObject) arg.AsyncState;
Socket handler = state.workSocket;
//Read data from the client socket.
int bytesRead = 0;
try
{
bytesRead = handler.EndReceive(arg);
}
catch (ObjectDisposedException ex)
{
Print("Process was terminated from another thread.");
}
if (bytesRead > 0)
{
//There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(
state.buffer,0,bytesRead));
//Check for end-of-file tag. If it is not there, read
//more data.
content = state.sb.ToString();
if (content.IndexOf("<EOF>") > -1)
{
content = content.Remove(content.Length-6);
//All the data has been read from the
//client. Display it on the console.
Print("Read " + content.Length + " bytes from socket. \n Data : " + content);
Respond(handler, content);
}
else
{
//Not all data received. Get more.
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
}
}
private void Send(Socket handler, String data)
{
//Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);
//Begin sending the data to the remote device.
handler.BeginSend(byteData,0,byteData.Length,0,
new AsyncCallback(SendCallback),handler);
}
private void SendCallback(IAsyncResult arg)
{
try
{
//Retrieve the socket from the state object.
Socket handler = (Socket) arg.AsyncState;
//Complete sending the data to the remote device.
int bytesSent = handler.EndSend(arg);
Print("Sent " + bytesSent + " bytes to client.");
handler.Shutdown(SocketShutdown.Both);
//need to make this not linger around
handler.LingerState = new LingerOption(true,1);
handler.Close();
}
catch (Exception e)
{
Print(e.ToString());
}
}
理想情况下,您将使用.NET线程池,这比为每个连接创建新线程更有效。 你可以分享你确切的“异步”代码 - 如果你在TCPListener上使用现有的异步模式,那么你可能已经在使用线程池了。
关于异常,当您的客户端与服务器断开连接时,您会看到这种情况。 是否在您设法接收所有数据之前发生了? 你在客户端刷新插座吗?
在完全崩溃服务器方面,只需继续测试,并记录任何全局未处理的异常。 这样你就可以了解可以预期的一切。
您可能希望看一下这篇文章 ,其中列出了一些需要检查的好东西。 例如,当您在套接字上使用.Listen()时,您的待办事项是什么?
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