Socket hanging on CLOSE_WAIT

Sharon

Hi Gurus,
I have a C# project on VS2008, Framework 3.5.
I'm using a TCP socket like that:

Socket mClientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
mClientSocket.NoDelay = true;
mClientSocket.Blocking = true;
mClientSocket.DontFragment = false;
mClientSocket.LingerState.Enabled = false;
mClientSocket.LingerState.LingerTime = 0;
mClientSocket.UseOnlyOverlappedIO = true;

// Get the remote IP address.
System.Net.IPAddress[] IPs = System.Net.Dns.GetHostAddresses(ExchangeIPAddress); // ExchangeIPAddress is a string with the IP address
IPAddress ip = IPs[0];
int iPortNo = System.Convert.ToInt32(ExchangePort);// ExchangePort is string with the port

// Create the end point.
IPEndPoint ipEnd = new IPEndPoint(ip, iPortNo);

// Connect to the remote host.
mClientSocket.Connect(ipEnd);

I have some cases that the socket is hanging on CLOSE_WAIT (shown on the Process Explorer), and stay like that forever, causing the data flow to cease.
There is no error return value anywhere, and no exception is thrown.
Therefore; I have no idea to what can cause this. Only closing the client application and starting it again, solve the problem. I this client restart is not acceptable solution.

Can anyone aid me to find what might cause this CLOSE_WAIT to hang like that?

--
Thanks
Sharon

2 Replies

Know the answer? Post it — somebody with the same question will find it here.

Sharon16y ago
Obviously, it occur after connect (can it be before connect?).
I'm using this socket to send data to the server by:
Int32 sentByteCount = 0;
do
{
sentByteCount += mClientSocket.Send(byData, sentByteCount, byData.Length - sentByteCount, SocketFlags.None);
}
while( sentByteCount < byData.Length );

and in any error/exception I'm doing:

mClientSocket.Disconnect(false);
mClientSocket.Shutdown(SocketShutdown.Both);
mClientSocket.Close();
mClientSocket = null;

And then creating the socket again and reconnecting as I posted before.

I can't be sure that no other error function fails, but in any case of an error, I'm writing it to a log, and the log is empty. So I believe there is no other error.
I'm also not sure the Connect was successful because I can't tell what can cause this hanging CLOSE_WAIT.

I'm simply in the blur…

--------
Thanks
Sharon
Sam Hobbs16y ago
I probably can't help much but I think it would help to get help if you are more clear about where in the program this occurs. Does it occur before or after the Connect? If after the Connect, then what else does the program do before the problem? Are you sure that there are not any other functions that fail? Are you sure that the Connect was successful?