Question

I have a python code that connects to IMAP server via IMAP4_SSL, and everything works fine until it tries to close the connection with this:

def logout(self):
    "Close the mailbox and logout and set the connection to None"
    try:
        self.connection.close()
        self.connection.logout()
    except e:
        pass
    self.connection = None

This leaves the connection in CLOSE_WAIT state:

 tcp       38      0 1.2.3.4:55809        5.6.7.8:993 CLOSE_WAIT  18983/python2.6

Where it remains for a prolonged time. The python process itself is a long-running daemon that does IMAP checks periodically, so these accumulate with time. Any ideas why it might be happening and what I am doing wrong?

Answer 1

Sockets hang out in CLOSE_WAIT when they haven’t been closed by the local program.

Looking at the imaplib source, the only place that self.sock.close() is called is in shutdown().

My guess is you need to call self.connection.shutdown().

update: As Bruno notes, logout() calls shutdown(). However, the way the example code is structured, if close() raises an exeception then logout()will be silently skipped… and shutdown() won’t be called. I wonder if that’s what’s going on.