'Start monitors, or restart after a fork.
Hold the lock when calling this.'

def _ensure_opened(self):

    if (not self._opened):
        self._opened = True
        self._update_servers()
        if (self._publish_tp or self._publish_server):
            self.__events_executor.open()
    else:
        for server in itervalues(self._servers):
            server.open()
