'Activate the poller'

def activate_poller(self):

    self._init_poller()
    fd_to_events = defaultdict(int)
    for (event, file_descriptors) in self._fd_events.items():
        for fileno in file_descriptors:
            fd_to_events[fileno] |= event
    for (fileno, events) in fd_to_events.items():
        self._register_fd(fileno, events)
