"""Check if the DagFileProcessorManager process is alive, and process any pending messages."""
        if not self._parent_signal_conn:
            raise ValueError("Process not started.")
        
        while self._parent_signal_conn.poll(timeout=0.01):
            try:
                result = self._parent_signal_conn.recv()
            except (EOFError, ConnectionError):
                break
            self._process_message(result)
        
        self._heartbeat_manager()
    def _process_message(self, message):
        self.log.debug("Received message of type %s", type(message).__name__)
        if isinstance(message, DagParsingStat):
            self._sync_metadata(message)
        else:
            raise RuntimeError(f"Unexpected message received of type {type(message).__name__}")
    def _heartbeat_manager(self):