avoid oprhan connections after socket.ShutDown

[titotarantula2001]

using TcpView you will see many orphan connections, loosing their process(id). After some time (1 Min), the connection will be close by the OS. (use-case: The image shows the connections, login/logout in to a Sftp-Server every 5 sec, to check for new files)

To avoid oprhan connections [TimeWait) add a delay of 100ms! I think, the wait leads to a direct thread-change to fullfill the sending the disconnect message!?

Insert a delay of 100ms between
-> TryDisconnectSend
add the delay of 100ms
-> socket.ShutDown()

In Session.cs
...

    private void Disconnect(DisconnectReason reason, string message)
    {
        // transition to disconnecting state to avoid throwing exceptions while cleaning up, and to
        // ensure any exceptions that are raised do not overwrite the exception that is set
        _isDisconnecting = true;

        // send disconnect message to the server if the connection is still open (IsConnected is not correct!) 
        // and the disconnect message has not yet been sent
        //
        // note that this should also cause the listener loop to be interrupted as
        // the server should respond by closing the socket

        _socketDisposeLock.Wait();
        var socketConnected = _socket != null && _socket.IsConnected();
        _socketDisposeLock.Release();
        if (socketConnected || IsConnected)
        {
            using (var delayEvent = new ManualResetEvent(initialState: false))
            {
                TrySendDisconnect(reason, message);
                delayEvent.WaitOne(TimeSpan.FromMilliseconds(100));
            }
        }

        // disconnect socket, and dispose it
        SocketDisconnectAndDispose();
    }