':param file_path: a Python file containing Airflow DAG definitions
:type file_path: unicode
:param pickle_dags: whether to serialize the DAG objects to the DB
:type pickle_dags: bool
:param dag_id_whitelist: If specified, only look at these DAG ID\'s
:type dag_id_whitelist: list[unicode]
:param log_file: the path to the file where log lines should be output
:type log_file: unicode'

def __init__(self, file_path, pickle_dags, dag_id_white_list, log_file):

    self._file_path = file_path
    self._log_file = log_file
    self._result_queue = multiprocessing.Queue()
    self._process = None
    self._dag_id_white_list = dag_id_white_list
    self._pickle_dags = pickle_dags
    self._result = None
    self._done = False
    self._start_time = None
    self._instance_id = DagFileProcessor.class_creation_counter
    DagFileProcessor.class_creation_counter += 1
