https://github.com/apache/airflow/blob/main/airflow/dag_processing/manager.py#L773
"""Collect the result from any finished DAG processors."""
        ready = multiprocessing.connection.wait(
            self.waitables.keys() - [self._direct_scheduler_conn], timeout=0
        )
        for sentinel in ready:
            if sentinel is self._direct_scheduler_conn:
                continue
            processor = cast(DagFileProcessorProcess, self.waitables[sentinel])
            self.waitables.pop(processor.waitable_handle)
            self._processors.pop(processor.file_path)
            self._collect_results_from_processor(processor)
        self.log.debug("%s/%s DAG parsing processes running", len(self._processors), self._parallelism)
        self.log.debug("%s file paths queued for processing", len(self._file_path_queue))
    @staticmethod
    def _create_process(file_path, pickle_dags, dag_ids, dag_directory, callback_requests):
        """Creates DagFileProcessorProcess instance."""
        return DagFileProcessorProcess(
            file_path=file_path,
            pickle_dags=pickle_dags,
            dag_ids=dag_ids,
            dag_directory=dag_directory,
            callback_requests=callback_requests,
        )
    def start_new_processes(self):