def physical_cores(self):
        """Return the number of physical cpu cores on the system."""
        try:
            return self._physical_cores_base()
        except Exception as e:
            from rez.utils.logging_ import print_error
            print_error("Error detecting physical core count, defaulting to 1: %s"
                        % str(e))
        return 1
Return the number of physical cpu cores on the system.