Instance shutdown with libvirt hammers the DB

Here's the code that gets executed while an instance is being shut down (blamar has a fix pending for the instance state logic being flawed). I believe this loop hammers the DB (and libvirt / kvm) and there really should be (1) a sleep in there to avoid hammering libvirt and (2) something that doesn't hit the DB on every iteration (maybe don't update unless the state has changed?)

        while True:
            try:
                state = self.get_info(instance['name'])['state']
                db.instance_set_state(context.get_admin_context(),
                                      instance['id'], state)
                if state == power_state.SHUTDOWN:
                    break
            except Exception:
                db.instance_set_state(context.get_admin_context(),
                                      instance['id'],
                                      power_state.SHUTDOWN)
                break