How To Wait For Any Socket To Have Data?

I'm implementing a socket-client which opens several sockets at the same time. Any socket may have data at a different time and I want to execute code when any socket has data and

Solution 1:

You can use select.select for your problem:

sockets = [sock1, sock2, sock3]
while sockets:
    rlist, _, _ = select.select(sockets, [], [])
    for sock in rlist:
        do_stuff(sock)
        sockets.remove(sock)

Solution 2:

If you are on POSIX, take a look at select.poll:

import socket
importselect
p = select.poll()
s1 = socket.socket()
s2 = socket.socket()
# call connect on sockets here...
p.register(s1, select.POLLIN)
p.register(s2, select.POLLIN)
p.poll()

Solution 3:

If you're using Python 3.4 or newer there is the selectors module in the standard library. It will use the "best" I/O multiplexing implementation that your system offers (select, poll, kqueue...) There's a simple echo server example at the end of the documentation page https://docs.python.org/3/library/selectors.html

There's a backport of this for older Python versions available as well.