def _handle_signal(self, signum=None, frame=None):
        """Python signal handler (self.set_handler subscribes it for you)."""
        signame = self.signals[signum]
        self.bus.log('Caught signal %s.' % signame)
        self.bus.publish(signame)
Python signal handler (self.set_handler subscribes it for you).
cherrypy/process/plugins.py