to_deactivate.add(dag.dag_id)
            if to_deactivate:
                deactivated = (
                    session.query(DagModel)
                    .filter(DagModel.dag_id.in_(to_deactivate))
                    .update({DagModel.is_active: False}, synchronize_session="fetch")
                )
                if deactivated:
                    self.log.info("Deactivated %i DAGs which are no longer present in file.", deactivated)
                for dag_id in to_deactivate:
                    SerializedDagModel.remove_dag(dag_id)
                    self.log.info("Deleted DAG %s in serialized_dag table", dag_id)
            self.last_deactivate_stale_dags_time = timezone.utcnow()
    def _run_parsing_loop(self):
        
        if self._async_mode:
            poll_time = 0.0
        else:
            poll_time = None
        self._refresh_dag_dir()
        self.prepare_file_path_queue()
        max_callbacks_per_loop = conf.getint("scheduler", "max_callbacks_per_loop")
        if self._async_mode:
            
            
            self.start_new_processes()
        while True:
            loop_start_time = time.monotonic()
            ready = multiprocessing.connection.wait(self.waitables.keys(), timeout=poll_time)
            if self._direct_scheduler_conn is not None and self._direct_scheduler_conn in ready: