Question

Ok, so I have Python 2.5 and Windows XP. I was using select.select with a socket object. I tried it again and again, but whenever I run it, the thread it is in gives me an error like select.error(9, “Bad file descriptor”).
The code is something like this:

import socket, select
s = socket.socket()
s.bind((socket.gethostbyname(socket.gethostname()), 1312))
s.listen(5)
inputs = [s]
outputs = []
while True:
    r, w, e = select.select(inputs, outputs, inputs)
    for sock in r:
        if sock is s:
            inputs.append(s.accept()[0])
        else:
            print s
            print s.recv(1024)

Any info would be appreciated. Thanks!

Answer 1

1. You called select.select with no arguments. It should be something like: select.select(inputs, outputs, []).

2. In the else you need to use sock, not s (the server).

3. Once the peer disconnects from a previously connected socket, you should remove it from the inputs list. You can know the peer has disconnected if sock.recv() returns an empty string or raises a socket.error exception. If you don’t do this, you might end up feeding an invalid socket descriptor to select.select, causing the error you talked about.