def get_logger(log_file: Optional[str] = None, log_level: Optional[int] = None, file_mode: str = 'w'):
    """ Get logging logger

    Args:
        log_file: Log filename, if specified, file handler will be added to
            logger
        log_level: Logging level.
        file_mode: Specifies the mode to open the file, if filename is
            specified (if filemode is unspecified, it defaults to 'w').
    """
    if log_level is None:
        log_level = os.getenv('LOG_LEVEL', 'INFO').upper()
        log_level = getattr(logging, log_level, logging.INFO)
    logger_name = __name__.split('.')[0]
    logger = logging.getLogger(logger_name)
    logger.propagate = False
    if logger_name in init_loggers:
        add_file_handler_if_needed(logger, log_file, file_mode, log_level)
        return logger

    # handle duplicate logs to the console
    # Starting in 1.8.0, PyTorch DDP attaches a StreamHandler <stderr> (NOTSET)
    # to the root logger. As logger.propagate is True by default, this root
    # level handler causes logging messages from rank>0 processes to
    # unexpectedly show up on the console, creating much unwanted clutter.
    # To fix this issue, we set the root logger's StreamHandler, if any, to log
    # at the ERROR level.
    for handler in logger.root.handlers:
        if type(handler) is logging.StreamHandler:
            handler.setLevel(logging.ERROR)

    stream_handler = logging.StreamHandler()
    handlers = [stream_handler]

    is_worker0 = _is_local_master()

    if is_worker0 and log_file is not None:
        file_handler = logging.FileHandler(log_file, file_mode)
        handlers.append(file_handler)

    for handler in handlers:
        handler.setFormatter(logger_format)
        handler.setLevel(log_level)
        logger.addHandler(handler)

    if is_worker0:
        logger.setLevel(log_level)
    else:
        logger.setLevel(logging.ERROR)

    init_loggers[logger_name] = True

    logger.info_once = MethodType(info_once, logger)
    logger.warning_once = MethodType(warning_once, logger)
    return logger
 Get logging logger

    Args:
        log_file: Log filename, if specified, file handler will be added to
            logger
        log_level: Logging level.
        file_mode: Specifies the mode to open the file, if filename is
            specified (if filemode is unspecified, it defaults to 'w').
    
swift/utils/logger.py