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Increasing memory usage in socket client

I'm trying to develop a console application behaving as an asynchronous socket client in C#. You can see the code below:
public class StateObject
{
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 1024;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
}
class Program
{
private static readonly string hostIp = ConfigurationManager.AppSettings["HostIp"];
private static readonly int port = Int32.Parse(ConfigurationManager.AppSettings["HostPort"]);
private static Socket client;
private static ManualResetEvent connectDone = new ManualResetEvent(false);
private static ManualResetEvent sendDone = new ManualResetEvent(false);
private static ManualResetEvent receiveDone = new ManualResetEvent(false);
private static Thread receiveThread;
static int Main(string[] args)
{
EventLog appLog = new EventLog();
appLog.Source = "xApp";
try
{
IPHostEntry ipHostInfo = Dns.GetHostEntry(hostIp);
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(ipAddress, port);
// Create a TCP/IP socket.
client = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Connect to the remote endpoint.
client.BeginConnect(remoteEP,
new AsyncCallback(ConnectCallback), client);
connectDone.WaitOne();
// Send test data to the remote device.
Send(client, "Login Message");
sendDone.WaitOne();
receiveThread = new Thread((ThreadStart)delegate
{
while (true)
{
Receive(client);
receiveDone.WaitOne();
Thread.Sleep(1);
}
});
receiveThread.Start();
}
catch (Exception ex)
{
appLog.WriteEntry(
"An exception occured: " +
" ex: " + ex.ToString() +
" stack trace: " + ex.StackTrace,
System.Diagnostics.EventLogEntryType.Error);
}
return 0;
}
private static void Receive(Socket client)
{
try
{
// Create the state object.
StateObject state = new StateObject();
state.workSocket = client;
// Begin receiving the data from the remote device.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
private static void ReceiveCallback(IAsyncResult ar)
{
try
{
// Retrieve the state object and the client socket
// from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket client = state.workSocket;
// Read data from the remote device.
int bytesRead = client.EndReceive(ar);
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));
Console.WriteLine("Response received : {0}", state.sb.ToString());
string[] args = state.sb.ToString().Split(';');
switch (args[1])
{
case "CREATEBOOK":
ProcessInput(args);
break;
case "CONFIRMBOOK":
if (args[2] == "true")
{
ConfirmProcess();
}
break;
default:
break;
}
receiveDone.Set();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
private static void Send(Socket client, String data)
{
byte[] byteData = Encoding.Unicode.GetBytes(data);
client.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), client);
}
private static void SendCallback(IAsyncResult ar)
{
try
{
Socket client = (Socket)ar.AsyncState;
// Complete sending the data to the remote device.
int bytesSent = client.EndSend(ar);
Console.WriteLine("Sent {0} bytes to server.", bytesSent);
// Signal that all bytes have been sent.
sendDone.Set();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
private static void ConnectCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket client = (Socket)ar.AsyncState;
// Complete the connection.
client.EndConnect(ar);
Console.WriteLine("Socket connected to {0}",
client.RemoteEndPoint.ToString());
// Signal that the connection has been made.
connectDone.Set();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
}
When I'm debugging I see that the code does the work as expected but the memory size used by process is increasing every moment. I think that the reason of the memory leak is the following code piece:
receiveThread = new Thread((ThreadStart)delegate
{
while (true)
{
Receive(client);
receiveDone.WaitOne();
Thread.Sleep(1);
}
});
receiveThread.Start();
But I don't have any idea about the change I have to do. Do you have any tip?
Thanks in advance,

I think the problem is in your Receive method which you are calling in a while loop. Basically you are creating a new StateObject every time you loop around.
// Create the state object.
StateObject state = new StateObject();
Try and store the state object as a class variable and reuse it. Maybe add a Reset method if you need to re-initialilze it again. This article shows a way to build a very efficient asynchronous socket which you may find useful.

Unable to read data correctly from .Net socket in C#

I have a client and server class in C# that uses socket communication. The Server looks like this:
public class AsyncTcpServer
{
private Socket _server_socket;
private Socket _client_socket;
private byte[] _receive_buffer;
private byte[] _send_buffer;
private NetworkStream _ns;
public void Start()
{
try
{
_server_socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
_server_socket.Bind(new IPEndPoint(IPAddress.Any, 17999));
_server_socket.Listen(0);
_server_socket.BeginAccept(new AsyncCallback(BeginAccept), null);
}
catch(Exception e)
{
Debug.Print(e.Message);
}
}
private void BeginAccept(IAsyncResult ar)
{
try
{
_client_socket = _server_socket.EndAccept(ar);
_receive_buffer = new byte[_client_socket.ReceiveBufferSize];
_send_buffer = new byte[_client_socket.ReceiveBufferSize];
_ns = new NetworkStream(_client_socket);
_client_socket.BeginReceive(_receive_buffer, 0, _receive_buffer.Length, SocketFlags.None, new AsyncCallback(RecieveCallback), null);
}
catch(Exception e)
{
Debug.Print(e.Message);
}
}
private void RecieveCallback(IAsyncResult ar)
{
try
{
string text = Encoding.ASCII.GetString(_receive_buffer);
Debug.Print("Server Received: " + text);
}
catch (Exception e)
{
Debug.Print("Unexpected exception: " + e.Message);
}
}
public void Send(byte [] bytes)
{
try
{
_ns.Write(bytes, 0, bytes.Length);
}
catch (Exception e)
{
Debug.Print("Unexpected exception: " + e.Message);
}
}
}
And the client looks like this:
public class AsyncTcpClient
{
private Socket _client_socket;
private byte[] _buffer;
private const int HEADER_SIZE = sizeof(int);
public void Start()
{
_client_socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
_client_socket.BeginConnect(new IPEndPoint(IPAddress.Loopback, 17999), new AsyncCallback(ConnectCallback), null);
}
private void ConnectCallback(IAsyncResult ar)
{
try
{
_client_socket.EndConnect(ar);
_buffer = new byte[_client_socket.ReceiveBufferSize];
StartReceive();
byte[] buffer = Encoding.ASCII.GetBytes("Connected!");
_client_socket.Send(buffer);
}
catch (Exception e)
{
Debug.Print(e.Message);
}
}
private void StartReceive(int offset = 0)
{
try
{
_client_socket.BeginReceive(_buffer, offset, _buffer.Length, SocketFlags.None, new AsyncCallback(RecieveCallback), null);
}
catch (Exception e)
{
Debug.Print(e.Message);
}
}
private void RecieveCallback(IAsyncResult ar)
{
try
{
int bytes_processed = 0;
int bytes_read = _client_socket.EndReceive(ar);
if (bytes_read > 0)
{
NetworkStream ns = new NetworkStream(_client_socket);
while (ns.DataAvailable && (bytes_processed < bytes_read))
{
byte[] len_bytes = new byte[HEADER_SIZE];
ns.Read(len_bytes, 0, HEADER_SIZE);
int current_chunk_size = BitConverter.ToInt32(len_bytes, 0);
if (current_chunk_size > 0)
{
byte[] data_buff = new byte[current_chunk_size];
ns.Read(data_buff, 0, current_chunk_size);
string s = Encoding.ASCII.GetString(data_buff);
bytes_processed += (HEADER_SIZE + current_chunk_size);
Debug.WriteLine(s);
}
}
}
StartReceive();
}
catch (Exception e)
{
Debug.Print(e.Message);
}
StartReceive();
}
}
They work together as follows:
Server starts
Client connects
Server sends custom packets to the client for its comsumption
I use the following 'data structure' to package my transmission data on the server side to send to the client:
{[DATA_LENGTH_IN_BYTES][PAYLOAD_BYTES]}
On the client side, I parse the first 4 bytes (sizeof(int)) to determine the payload length and then parse the payload itself. This works the first time I do it but after that the DataAvailable member of the NetworkStream is false and I can't parse the rest of the payload.
Why is DataAvailable false? I'm pretty new to doing this stuff in C# - am I approaching it the wrong way entirely?
Thanks in Advance!

Here is the solution I settled on:
Server:
public class Listener
{
private TcpListener _listener;
private TcpClient _client;
public void Start()
{
_listener = new TcpListener(IPAddress.Loopback, 17999);
_listener.Start();
_listener.BeginAcceptTcpClient(new AsyncCallback(AcceptTcpClientCallback), _listener);
}
private void AcceptTcpClientCallback(IAsyncResult ar)
{
try
{
Debug.WriteLine("Accepted tcp client callback");
_client = _listener.EndAcceptTcpClient(ar);
}
catch (Exception e)
{
Debug.WriteLine(e.Message);
}
}
public void Write(string data)
{
try
{
NetworkStream ns = _client.GetStream();
byte[] buffer = Encoding.ASCII.GetBytes(data);
ns.Write(buffer, 0, buffer.Length);
}
catch (Exception e)
{
Debug.WriteLine(e.Message);
}
}
}
And the client:
public class Client
{
private TcpClient _client;
private byte[] _buffer;
public void Start()
{
try
{
_client = new TcpClient();
_client.BeginConnect(IPAddress.Loopback, 17999, new AsyncCallback(ConnectCallback), _client);
}
catch (Exception e)
{
Debug.WriteLine(e.Message);
}
}
private void ConnectCallback(IAsyncResult ar)
{
try
{
NetworkStream ns = _client.GetStream();
_buffer = new byte[_client.ReceiveBufferSize];
ns.BeginRead(_buffer, 0, _buffer.Length, new AsyncCallback(ReadCallback), null);
}
catch (Exception e)
{
Debug.WriteLine(e.Message);
}
}
private void ReadCallback(IAsyncResult ar)
{
try
{
NetworkStream ns = _client.GetStream();
int read = ns.EndRead(ar);
string data = Encoding.ASCII.GetString(_buffer, 0, read);
var res = data.Split(new [] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries);
foreach (var r in res)
{
Debug.WriteLine(r); // process messages
}
ns.BeginRead(_buffer, 0, _buffer.Length, ReadCallback, _client);
}
catch (Exception e)
{
Debug.WriteLine(e.Message);
}
}
}
Where messages from the server to the client are formed as follows:
string message = "This is a message" + "\r\n";
_listener.Send(message);
I like this alternative for its simplicity. Its a lot shorter and (to me at least) much easier to manage.
HTH

I think you forget the EndReceive in the RecieveCallback. (server code)
private void RecieveCallback(IAsyncResult ar)
{
try
{
int bytesReceived = _client_socket.EndReceive(ar); // <---
string text = Encoding.ASCII.GetString(_receive_buffer);
Debug.Print("Server Received: " + text);
}
catch (Exception e)
{
Debug.Print("Unexpected exception: " + e.Message);
}
}
I advise to create one class that reads/writes to sockets (implementing the protocol). A Base class that handles reads/writes to Sockets, a client socket that is derived from the SocketConnection, but first will connect to an ipendpoint. A server that has a List of SocketConnection. This way you keep your client/server functionality separated of the message handling on socket. But both using the same code to receive/send messages. Here is an example:
Pseudo:
// base class that handle receive/sent packets
class SocketConnection
{
// the reason for a Start method is that event can be bound before the Start is executed.
void Start(Socket socket)
{
StartReceive();
}
void StartReceive()
{
socket.BeginReceive(...);
}
void EndReceive()
{
socket.EndReceive(...);
// handle received message.
// call the ondata event or something
StartReceive();
}
}
class ClientSocket : SocketConnection
{
void Connect()
{
Socket socket = new Socket(...);
socket.Connect(..);
// start receiving from the client socket.
base.Start(socket);
}
}
class Server
{
List<SocketConnection> _clients;
void Start()
{
// Create server socket + listening etc..
StartAccept();
}
void StartAccept()
{
serverSocket.BeginAccept(...);
}
void EndAccept()
{
Socket serverClientSocket = EndAccept(...);
// create a base socket handler.....
SocketConnection clientSocket = new SocketConnection();
_clients.Add(clientSocket);
// bind the ondata event of the client and pass it to the clientondata event of the server.
// Start receiving from the socket.
clientSocket.Start(serverClientSocket);
// accept new clients.
StartAccept();
}
}
UPDATE:
"Regarding how to handle buffers, what would you suggest as the best way to not miss data in separate packets?"
I would send a size first:
// sending part.
string message = "This is a message";
byte[] buffer = Encoding.ASCII.GetBytes(message);
_client_socket.Send(BitConverter.GetBytes(buffer.Length)); // sends a int as 4 bytes.
_client_socket.Send(data);
// receiving part.
// try to receive at least 4 bytes. (no more/ no less)
int length = BitConverter.ToInt32(buffer, 0);
// try to receive data with `length` size, (no more/ no less)
This will separate different packets.
Asynchronous example:
You still need to add some exception handling code.
public static class SocketReader
{
public static void ReadFromSocket(Socket socket, int count, Action<byte[]> endRead)
{
// read from socket, construct a new buffer.
DoReadFromSocket(socket, 0, count, new byte[count], endRead);
}
public static void ReadFromSocket(Socket socket, int count, ref byte[] buffer, Action<byte[]> endRead)
{
// if you do have a buffer available, you can pass that one. (this way you do not construct new buffers for receiving.
// the ref is because if the buffer is too small, it will return the newly created buffer.
// if the buffer is too small, create a new one.
if (buffer.Length < count)
buffer = new byte[count];
DoReadFromSocket(socket, 0, count, buffer, endRead);
}
// This method will continues read until count bytes are read. (or socket is closed)
private static void DoReadFromSocket(Socket socket, int bytesRead, int count, byte[] buffer, Action<byte[]> endRead)
{
// Start a BeginReceive.
socket.BeginReceive(buffer, bytesRead, count - bytesRead, SocketFlags.None, (result) =>
{
// Get the bytes read.
int read = socket.EndReceive(result);
// if zero bytes received, the socket isn't available anymore.
if (read == 0)
{
endRead(new byte[0]);
return;
}
// increase the bytesRead, (index point for the buffer)
bytesRead += read;
// if all bytes are read, call the endRead with the buffer.
if (bytesRead == count)
endRead(buffer);
else
// if not all bytes received, start another BeginReceive.
DoReadFromSocket(socket, bytesRead, count, buffer, endRead);
}, null);
}
}
Example how to use it:
Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
// read header. (length of data) (4 bytes)
SocketReader.ReadFromSocket(socket, 4, (headerBuffer) =>
{
if (headerBuffer.Length == 0)
{
// disconnected;
return;
}
int length = BitConverter.ToInt32(headerBuffer, 0);
// read bytes specified in length.
SocketReader.ReadFromSocket(socket, length, (dataBuffer) =>
{
if (dataBuffer.Length == 0)
{
// disconnected;
return;
}
// if you want this in a stream, you can do: This way the stream is readonly and only wraps arround the bytearray.
using (MemoryStream stream = new MemoryStream(dataBuffer, 0, length))
using (StreamReader reader = new StreamReader(stream))
while (!reader.EndOfStream)
Debug.WriteLine(reader.ReadLine());
});
});

Client receiving packet only on close

Basically I made two C# applications, a client and a server. The client connects to the server (via sockets), then sends a packet containing some text, and the server should reply.
My problem is: the server sends (or the client receives) the response packet only when it closes (ALT+F4). I'd like some help. I'll copypaste below the source code for both the projects.
Client:
public class StateObject
{
public Socket skt = null;
public const int BufferSize = 256;
public byte[] buffer = new byte[BufferSize];
public StringBuilder sb = new StringBuilder();
}
public class AsynchronousClient
{
private const int port = 11000;
private static ManualResetEvent connectDone =
new ManualResetEvent(false);
private static ManualResetEvent sendDone =
new ManualResetEvent(false);
private static ManualResetEvent receiveDone =
new ManualResetEvent(false);
private static String response = String.Empty;
public static string command;
public static Socket client;
public static void StartClient()
{
try
{
IPHostEntry ipHostInfo = Dns.GetHostEntry(IPAddress.Parse("127.0.0.1"));
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(IPAddress.Parse("127.0.0.1"), port);
client = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
client.BeginConnect(remoteEP,
new AsyncCallback(ConnectCallback), client);
connectDone.WaitOne();
while (true)
{
command = Console.ReadLine();
if (command == "exit")
{
Console.WriteLine("Terminating...");
client.Shutdown(SocketShutdown.Both);
client.Close();
Environment.Exit(0);
}
else
{
Send(client, command + "<EOF>");
sendDone.WaitOne();
Receive(client);
receiveDone.WaitOne();
Console.WriteLine("Response received : {0}", ProcessResponse(response));
client.Shutdown(SocketShutdown.Both);
client.Close();
}
//Console.CancelKeyPress += (sender, e) =>
//{
// Console.WriteLine("Terminating...");
// client.Shutdown(SocketShutdown.Both);
// client.Close();
// Environment.Exit(0);
//};
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
static public string ProcessResponse(string pkt)
{
string response = null;
response = pkt.Replace("<EOF>","");
return response;
}
private static void ConnectCallback(IAsyncResult ar)
{
try
{
Socket client = (Socket)ar.AsyncState;
client.EndConnect(ar);
Console.WriteLine("Socket connected to {0}",
client.RemoteEndPoint.ToString());
connectDone.Set();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
private static void Receive(Socket client)
{
try
{
StateObject state = new StateObject();
state.skt = client;
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
private static void ReceiveCallback(IAsyncResult ar)
{
try
{
StateObject state = (StateObject)ar.AsyncState;
Socket client = state.skt;
int bytesRead = client.EndReceive(ar);
if (bytesRead > 0)
{
state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
else
{
if (state.sb.Length > 1)
{
response = state.sb.ToString();
}
receiveDone.Set();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
private static void Send(Socket client, String data)
{
byte[] byteData = Encoding.ASCII.GetBytes(data);
client.BeginSend(byteData, 0, byteData.Length, 0, new AsyncCallback(SendCallback), client);
}
private static void SendCallback(IAsyncResult ar)
{
try
{
Socket client = (Socket)ar.AsyncState;
int bytesSent = client.EndSend(ar);
Console.WriteLine("Sent {0} bytes to server.", bytesSent);
sendDone.Set();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
public static int Main(String[] args)
{
StartClient();
return 0;
}
Server:
public class Program
{
public class StateObject
{
public Socket skt = null;
public const int buffersize = 1024;
public byte[] buffer = new byte[buffersize];
public StringBuilder sb = new StringBuilder();
}
public class AsynchronousSocketListener
{
public static ManualResetEvent allDone = new ManualResetEvent(false);
public AsynchronousSocketListener() { }
public static Socket handler;
public static void StartListening()
{
byte[] bytes = new Byte[1024];
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 11000);
Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
try
{
listener.Bind(localEndPoint);
listener.Listen(100);
while (true)
{
allDone.Reset();
Console.WriteLine("Waiting for a connection...");
listener.BeginAccept(
new AsyncCallback(AcceptCallback),
listener);
allDone.WaitOne();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
Console.WriteLine("\nPress ENTER to continue...");
Console.Read();
}
public static void AcceptCallback(IAsyncResult ar)
{
allDone.Set();
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);
StateObject state = new StateObject();
state.skt = handler;
handler.BeginReceive(state.buffer, 0, StateObject.buffersize, 0, new AsyncCallback(ReadCallback), state);
}
public static void ReadCallback(IAsyncResult ar)
{
String content = String.Empty;
StateObject state = (StateObject)ar.AsyncState;
Socket handler = state.skt;
int bytesRead = handler.EndReceive(ar);
if (bytesRead > 0)
{
state.sb.Append(Encoding.ASCII.GetString(
state.buffer, 0, bytesRead));
content = state.sb.ToString();
if (content.IndexOf("<EOF>") > -1)
{
Console.WriteLine("Read {0} bytes from socket. \n Data : {1}", content.Length, ProcessResponse(content));
Send(handler, content);
}
else
{
handler.BeginReceive(state.buffer, 0, StateObject.buffersize, 0,
new AsyncCallback(ReadCallback), state);
}
}
}
private static void Send(Socket handler, String data)
{
byte[] byteData = Encoding.ASCII.GetBytes(data);
handler.BeginSend(byteData, 0, byteData.Length, 0, new AsyncCallback(SendCallback), handler);
}
private static void SendCallback(IAsyncResult ar)
{
try
{
handler = (Socket)ar.AsyncState;
int bytesSent = handler.EndSend(ar);
Console.WriteLine("Sent {0} bytes to client.", bytesSent);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
static public string ProcessResponse(String pkt)
{
string response = null;
response = pkt.Replace("<EOF>", "");
return response;
}
}
public static void Main(string[] args)
{
AsynchronousSocketListener.StartListening();
}
}

In your Client receive callback:
private static void ReceiveCallback(IAsyncResult ar)
{
try
{
StateObject state = (StateObject)ar.AsyncState;
Socket client = state.skt;
int bytesRead = client.EndReceive(ar);
if (bytesRead > 0)
{
state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
else
{
if (state.sb.Length > 1)
{
response = state.sb.ToString();
}
receiveDone.Set();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
You won't ever drop down into the else block unless the socket is explicitly closed (or there is some kind of other error in the connection). Therefore receiveDone never gets set and your main loop is simply stuck waiting for a "response".
If you want to process a "complete message" when it comes in, then check for your <EOF> value after you append the current string to your buffer like this:
if (bytesRead > 0)
{
state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));
// it's not a "response" unless it's terminated with "<EOF>" right?
response = state.sb.ToString();
if (response.IndexOf("<EOF>") != -1)
{
state.sb.Clear();
receiveDone.Set();
}
else
{
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
}
else
{
if (state.sb.Length > 1)
{
response = state.sb.ToString(); // this is a partial response, not terminated with "<EOF>"
}
receiveDone.Set();
}
Note that response mechanism being used is extremely limited as it would fail for multiple messages coming in at the same time like: Hello<EOF> World!<EOF> It would treat those two messages as one long message. (I realize your example is only sending one "message".)
You're almost certainly going to have to deal with that scenario in any real world application that sends "control" messages in addition to "content" messages. To handle that you'd look for <EOF> using IndexOf() and extract the text up to that point and process that "complete message". Afterwards you'd keep looping as long as <EOF> is still found to process the other pending messages. You'd also have to REMOVE those processed complete messages from the StringBuilder in such a way that any remaining values after the <EOF> are left in place so that when partial messages come in the new data can be appended to the existing data. This is because your data can also be split up when it is sent, resulting in multiple "chunks" of data being received even though it is logically one "complete message" when you sent it. So one send with Complete Message<EOF> could result in one or more receives such as Comp followed by lete Message<EOF>. Your code has to be able to deal with these realities of TCP communication...

Send a message back to a list of clients at any given time with async sockets in C#

Ive got an async server set up, it works perfectly by connecting, receiving and sending back a message to the connecting client.
The server itself is a Game-World-Server (mmorpg style). When a user sends its position to where its located, I need to push this out to all the clients with a PlayerPositionNotice. I know I'm missing some basic stuff here, but when i try to save the StateObject that was created in the accept method, and use that socket to send back information to the player at any given time it fails because the socket is closed. =/ Don't know why this happens and would I've searched a couple of engines on this but came back empty.
This is how i created my server:
First off we have the global stuff:
public StateManager _stateManager = new StateManager();
public bool IsClosing = false;
private const int _port = 1025;
private IPHostEntry _localhost;
private IPEndPoint _endpoint;
private Socket _serverSocket;
private Thread _serverThread;
Second of we have the initialize stuff:
public void Start()
{
_serverThread = new Thread(Initialize);
_serverThread.Start();
}
/// <summary>
/// Main entry point for the server
/// </summary>
private void Initialize()
{
Console.WriteLine("Server Main Socket Thread Initialized.");
_localhost = Dns.GetHostEntry(Dns.GetHostName());
try
{
_endpoint = new IPEndPoint(_localhost.AddressList[0], _port);
_serverSocket = new Socket(_endpoint.Address.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
_serverSocket.Bind(_endpoint);
_serverSocket.Listen(100);
_serverSocket.BeginAccept(new AsyncCallback(acceptCallback), _serverSocket);
}
catch (ArgumentOutOfRangeException)
{
Console.WriteLine(" >> Port number " + _port + " would seem to be invalid, should be between 1024 and 65000");
}
catch (SocketException)
{
Console.WriteLine(" >> Could not create socket, check to make sure not duplicating port");
}
catch (Exception e)
{
Console.WriteLine(" >> Error occured while binding socket, IE:" + e.InnerException);
}
}
So far so good, i expect.. And now to the rest of the server class.
private void acceptCallback(IAsyncResult result)
{
Console.WriteLine("Connection Accepted");
StateObject state = null;
try
{
state = new StateObject
{
workSocket = ((Socket)result.AsyncState).EndAccept(result)
};
_stateManager.AddConnection(state);
state.workSocket.BeginReceive(state.buffer, 0, state.buffer.Length,
SocketFlags.None, new AsyncCallback(receiveCallback), state);
_serverSocket.BeginAccept(new AsyncCallback(acceptCallback), _serverSocket);
}
catch (SocketException)
{
_stateManager.RemoveConnection(state);
_serverSocket.BeginAccept(new AsyncCallback(acceptCallback), _serverSocket);
}
catch (Exception)
{
_stateManager.RemoveConnection(state);
_serverSocket.BeginAccept(new AsyncCallback(acceptCallback), _serverSocket);
}
}
private void receiveCallback(IAsyncResult result)
{
var state = (StateObject)result.AsyncState;
try
{
// Buffer and count bytes read
int bytesRead = state.workSocket.EndReceive(result);
if (!state.workSocket.Connected)
_stateManager.RemoveConnection(state);
if (bytesRead > 0)
{
// Parse the message to the protocol manager and return a reply
var replyingData = ProtocolManager.Parse(state.buffer);
if (replyingData != null)
Send(replyingData, state);
//Queue the next receive
state.workSocket.BeginReceive(state.buffer, 0, state.buffer.Length, SocketFlags.None, new AsyncCallback(receiveCallback), state);
}
else
{
_stateManager.RemoveConnection(state);
}
}
catch (SocketException e)
{
_stateManager.RemoveConnection(state);
}
}
public bool Send(byte[] message, StateObject state)
{
Console.WriteLine("Sending " + message.Length + " bytes");
if (state != null && state.workSocket.Connected)
{
lock (state.workSocket)
{
//we use a blocking mode send, no async on the outgoing
//since this is primarily a multithreaded application, shouldn't cause problems to send in blocking mode
state.workSocket.Send(message, message.Length, SocketFlags.None);
}
}
else return false;
return true;
}
The stateManager contains a list of StateObject.. Below you can see how i build them.
STATE MANAGER:
public class StateManager
{
private List<StateObject> _connections = new List<StateObject>();
public void AddConnection(StateObject so)
{
lock (_connections)
{
_connections.Add(so);
}
}
public void RemoveConnection(StateObject so)
{
if (so.workSocket != null)
{
so.workSocket.Close();
lock (_connections)
{
_connections.Remove(so);
}
}
}
}
STATE OBJECT
public class StateObject
{
public Socket workSocket = null;
public const int BufferSize = 1024;
public byte[] buffer = new byte[BufferSize];
public StringBuilder sb = new StringBuilder();
}
My problem here is that whenever anybody in this list sends something i want to send back a notice to alot of other clients. How and where can i implement this? Anybody that can kick me in the right direction? =)

This code seem to be correct and I don't know why you get "socket is closed" error, but there is another problem: in Send(byte[] message, StateObject state) method, because you call this when receiving from user and send received data back to that user.(not to all other users to notice them)
As you said, if you need to send new location to all other users:
Call this method instead of your Send(byte[] message, StateObject state), when received new location.
public void NoticeAllusers(byte []buffer,StateObject state)
{
foreach(StateObject obj in _stateManager._connections)
{
if (obj != state)
{
obj.workSocket.BeginSend(buffer,<parameters you>...., new AsyncCallback(OnSend) state.workSocket);
}
}
}
public void OnSend(IAsyncResult ar)
{
try
{
Socket sock = (Socket)ar.AsyncState;
sock.EndSend(ar);
}
catch { }
}
I hope it will help a little :)

TCP server causes MAX CPU utlization

i write this TCP communication library. the problem is that. when a client connects. the CPU usages boosts to maximum....this causes other application to become slow...
please take a look at the code and correct me where i did wrong..
the main code of my TCP library is
TCP Server Class
public class TCPServerEndPoint : ICommunication
{
private string channelName;
private string localIP;
private int localPort;
private string remoteIP;
private int remotePort;
private TcpListener tcpListenter;
/// <summary>
/// Accept the incomming connection and pass it to a thread to handle communication.
/// </summary>
private TCPServerWorker worker;
/// <summary>
/// List of threads created for connected clients.
/// </summary>
List<TCPServerWorker> workerThreads;
/// <summary>
/// Thread to keep listening process in seperate thread.
/// </summary>
private Thread serverThread;
/// <summary>
/// Flag to keep status of Endpoint.
/// </summary>
private bool keepRunning;
public TCPServerEndPoint()
{
this.keepRunning = false;
Guid guid = Guid.NewGuid();
channelName = guid.ToString();
workerThreads = new List<TCPServerWorker>();
}
public TCPServerEndPoint(string localIP, int localPort, string remoteIP, int remotePort)
{
this.localIP = localIP;
this.localPort = localPort;
this.remoteIP = remoteIP;
this.remotePort = remotePort;
workerThreads = new List<TCPServerWorker>();
this.keepRunning = false;
}
public event EventHandler<CommEventArgs> OnCommReceive;
public int CommStart()
{
if (this.IsStarted == true)
{
Console.WriteLine("TCP Server is already running");
return -1;
}
serverThread = new Thread(new ThreadStart(StartListening));
serverThread.IsBackground = true;
serverThread.Start();
return 0;
}
private void StartListening()
{
try
{
IPAddress localAddress = IPAddress.Parse(this.localIP);
tcpListenter = new TcpListener(localAddress, this.localPort);
tcpListenter.Start();
Console.WriteLine("TCP Server started");
Console.WriteLine("Server is listening on port : {0}", this.localPort);
this.keepRunning = true;
// look for incomming connections
while (this.keepRunning)
{
// connection received
TcpClient client = tcpListenter.AcceptTcpClient();
// create a new WorkerThread and pass the connected client to handle.
worker = new TCPServerWorker(client);
worker.dataReceived += new EventHandler<CommEventArgs>(worker_dataReceived);
workerThreads.Add(worker);
worker.Start();
}
tcpListenter.Stop();
Console.WriteLine("TCP Server stopped");
this.keepRunning = false;
}
catch
{
return;
}
}
void worker_dataReceived(object sender, CommEventArgs e)
{
if (this.OnCommReceive != null)
{
e.commChannel = this;
this.OnCommReceive(this, e);
}
}
public int CommStop()
{
if (this.IsStarted == false)
return -1;
// Close all worker threads created for connected clients.
foreach (TCPServerWorker item in workerThreads)
{
item.KeepRunning = false;
}
// break the listening loop
this.keepRunning = false;
// clear the worker thread list
workerThreads.Clear();
// force server to receive message to break while(keepRunning) loop
byte[] data = new byte[4];
IPEndPoint ipEndPoint = new IPEndPoint(IPAddress.Parse(this.localIP), localPort);
Socket tcpClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
tcpClient.Connect(ipEndPoint);
tcpClient.SendTo(data, ipEndPoint);
tcpClient.Close();
return 0;
}
public int CommSend(CommEventArgs obj)
{
obj.destAddress = this.remoteIP;
obj.destPort = this.remotePort;
return CommSendTo(obj);
}
public int CommSendTo(CommEventArgs obj)
{
int n;
byte[] buf;
try
{
IPEndPoint ipEndPoint = new IPEndPoint(IPAddress.Parse(obj.destAddress), obj.destPort);
buf = (byte[])obj.data;
Socket tcpClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
tcpClient.Connect(ipEndPoint);
n = tcpClient.SendTo(buf, ipEndPoint);
tcpClient.Close();
}
catch (Exception ex)
{
Console.WriteLine("Exception :: {0}", ex.Message);
return -1;
}
if (n == buf.Length)
{
if (OnCommSendComplete != null)
{
OnCommSendComplete(this, obj);
}
Console.WriteLine("Sent {0} bytes to {1}:{2}", n, obj.destAddress, obj.destPort);
}
else
{
return -1;
}
return n;
}
}
}
TCPServerWorker.cs
class TCPServerWorker
{
private TcpClient client;
private bool keepRunning;
public event EventHandler<CommEventArgs> dataReceived;
private const int MAX_TCP_DATA = 64000;
public bool KeepRunning
{
get
{
return this.keepRunning;
}
set
{
this.keepRunning = value;
}
}
public TCPServerWorker(TcpClient client)
{
this.client = client;
this.keepRunning = false;
}
public void Start()
{
Thread thread = new Thread(new ThreadStart(Process));
thread.IsBackground = true;
thread.Start();
}
private void Process()
{
if (client.Connected == true)
{
Console.WriteLine("Client connected :: {0}", client.Client.RemoteEndPoint);
this.keepRunning = true;
while (this.keepRunning)
{
// in my view. here is the main problem. this loop run for infinite time and causes CPU to reach at 100
byte[] buffer = new byte[MAX_TCP_DATA];
NetworkStream stream = client.GetStream();
StreamWriter writer = new StreamWriter(client.GetStream());
if (stream.DataAvailable == true)
{
int receivedBytesCount = stream.Read(buffer, 0, buffer.Length);
byte[] receivedBuffer = new byte[receivedBytesCount];
Array.Copy(buffer, receivedBuffer, receivedBytesCount);
String msg = Encoding.UTF8.GetString(receivedBuffer);
Console.WriteLine("Received MSG ::: " + msg);
writer.WriteLine("Server : Received {0} bytes", receivedBytesCount);
CommEventArgs comEventArg = new CommEventArgs();
comEventArg.data = (byte[])receivedBuffer;
IPEndPoint remoteIPEndPoint = (IPEndPoint)client.Client.RemoteEndPoint;
comEventArg.srcAddress = remoteIPEndPoint.Address.ToString();
comEventArg.srcPort = remoteIPEndPoint.Port;
comEventArg.length = receivedBytesCount;
this.OnDataReceived(comEventArg);
writer.Flush();
}
}
client.Close();
}
}
protected void OnDataReceived(CommEventArgs e)
{
if (this.dataReceived != null)
{
this.dataReceived(this, e);
}
}
}
}

You're using nonblocking I/O which leads to a loop (at least) in your client
while (this.keepRunning) {...}
which is consuming all your CPU resources by busy waiting.
You should consider to use blocking I/O or Socket.Select
Look at the first remark here
Details about select

One thing to note is that you never SET IsStarted .. you only GET it ._. Maybe you're spawning hundreds of threads =/ I'm talking about the TCPServerEndPoint class =/

Yes, you are busy waiting for a connection. I don't know socket programming so I can't give you details, but what you need to do is wait for a connection using the blocking system call.

I solved the issue after modifying the Process method of TCPServerWorker.cs
here is the changes
private void Process()
{
if (client.Connected == true)
{
Console.WriteLine("Client connected :: {0}", client.Client.RemoteEndPoint);
Byte[] bytes = new Byte[MAX_TCP_DATA];
String data = null;
NetworkStream stream = client.GetStream();
int i;
try
{
// Loop to receive all the data sent by the client.
while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
{
// bytes contains received data in byte[].
// Translate data bytes to a UTF-8 string.
byte[] receivedBuffer = new byte[i];
Array.Copy(bytes, receivedBuffer, i);
data = System.Text.Encoding.UTF8.GetString(receivedBuffer);
Console.WriteLine("Received MSG ::: " + data);
// Process the data sent by the client.
byte[] msg = System.Text.Encoding.UTF8.GetBytes(data);
// Send back a response.
stream.Write(msg, 0, msg.Length);
CommEventArgs comEventArg = new CommEventArgs();
comEventArg.data = receivedBuffer;
IPEndPoint remoteIPEndPoint = (IPEndPoint)client.Client.RemoteEndPoint;
comEventArg.srcAddress = remoteIPEndPoint.Address.ToString();
comEventArg.srcPort = remoteIPEndPoint.Port;
comEventArg.length = i;
this.OnDataReceived(comEventArg);
}
}
catch (Exception ex)
{
Console.WriteLine("Exception : " + ex.Message);
}
finally
{
client.Close();
}
}
}