Send a signal to all children

        :param int signum: The signal to send

def signal_children(self, signum):
        """Send a signal to all children

        :param int signum: The signal to send

        """
        LOGGER.info('Sending signal %i to children', signum)
        for child in self.living_children:
            if child.pid != os.getpid():
                os.kill(child.pid, signum)