https://github.com/apache/airflow/blob/main/airflow/dag_processing/manager.py#L773
"""Stops all running processors."""
        for processor in self._processors.values():
            Stats.decr(
                "dag_processing.processes", tags={"file_path": processor.file_path, "action": "terminate"}
            )
            processor.terminate()
    def end(self):
        """Kill all child processes on exit since we don't want to leave them as orphaned."""
        pids_to_kill = self.get_all_pids()
        if pids_to_kill:
            kill_child_processes_by_pids(pids_to_kill)
    def emit_metrics(self):
        """
        Emit metrics about dag parsing summary.
        This is called once every time around the parsing "loop" - i.e. after
        all files have been parsed.
        """
        parse_time = time.perf_counter() - self._parsing_start_time
        Stats.gauge("dag_processing.total_parse_time", parse_time)
        Stats.gauge("dagbag_size", sum(stat.num_dags for stat in self._file_stats.values()))
        Stats.gauge(
            "dag_processing.import_errors", sum(stat.import_errors for stat in self._file_stats.values())
        )
    @property
    def file_paths(self):
        return self._file_paths