Hi everyone, I am in the process of learning how to use select to run a server that can handle multiple clients. I have not been able to find any server examples which implement Try/Catch Exception errors, which I believe is the root of my problems.

Basically the server works fine by receiving a message from the client, prints it to the screen, then apparently will know a client has disconnected by not receiving any bytes from him. When I close my client, the server throws a 10054 error message: "An existing connection was forcibly closed by the remote host".

I THINK this is just the server telling me that the client socket has been closed by means not related to the server actually running socket.close() which is true... How can I get it to do this cleanly without crashing the server?

Here is my code: I pride myself on decent code structure so you shouldn't have much trouble figuring out what is going on.


import socket
import select

# Server attributes
HOST = ''     # Host address
PORT = 6006   # Host port
BACKLOG = 5   # Number of queued connections
BUFFER = 1024 # Data buffer size

# Initialize server
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind((HOST, PORT))

clients = [] # Container for all open sockets

while True:
    inputready, outputready, errors = select.select( [server] + clients, [], [] )
    for socket in inputready:
        if socket == server:
            # Handle server socket
            client, address = server.accept()
            print "Received a connection from ", address
            # Handle all other sockets
            data = socket.recv(BUFFER)
            if data:
                print "Received:", data


import socket

# Client attributes
HOST = 'localhost' # Host address
PORT = 6006        # Host port
BUFFER = 1024      # Data buffer size

# Initialize server connection
mySocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
mySocket.connect((HOST, PORT))

mySocket.send("I have connected!")
print mySocket.recv(BUFFER)

Another thing I could use help on if you are feeling nice - it only crashes when I hit the "X" on the client program. If I uncomment the last line on the client, it will still crash, but the server doesn't crash right away even when I thought it was going to because it is closing the socket. Why?

Wow.. I think it's because I forgot to comment out the client's receive.

It was crashing because the connection was dropped while waiting to receive data that was never being sent from the server in the first place.