def build_logger()

in fastchat/utils.py [0:0]


def build_logger(logger_name, logger_filename):
    global handler

    formatter = logging.Formatter(
        fmt="%(asctime)s | %(levelname)s | %(name)s | %(message)s",
        datefmt="%Y-%m-%d %H:%M:%S",
    )

    # Set the format of root handlers
    if not logging.getLogger().handlers:
        if sys.version_info[1] >= 9:
            # This is for windows
            logging.basicConfig(level=logging.INFO, encoding="utf-8")
        else:
            if platform.system() == "Windows":
                warnings.warn(
                    "If you are running on Windows, "
                    "we recommend you use Python >= 3.9 for UTF-8 encoding."
                )
            logging.basicConfig(level=logging.INFO)
    logging.getLogger().handlers[0].setFormatter(formatter)

    # Redirect stdout and stderr to loggers
    stdout_logger = logging.getLogger("stdout")
    stdout_logger.setLevel(logging.INFO)
    sl = StreamToLogger(stdout_logger, logging.INFO)
    sys.stdout = sl

    stderr_logger = logging.getLogger("stderr")
    stderr_logger.setLevel(logging.ERROR)
    sl = StreamToLogger(stderr_logger, logging.ERROR)
    sys.stderr = sl

    # Get logger
    logger = logging.getLogger(logger_name)
    logger.setLevel(logging.INFO)

    # if LOGDIR is empty, then don't try output log to local file
    if LOGDIR != "":
        os.makedirs(LOGDIR, exist_ok=True)
        filename = os.path.join(LOGDIR, logger_filename)
        handler = logging.handlers.TimedRotatingFileHandler(
            filename, when="D", utc=True, encoding="utf-8"
        )
        handler.setFormatter(formatter)

        for l in [stdout_logger, stderr_logger, logger]:
            if l in visited_loggers:
                continue
            visited_loggers.add(l)
            l.addHandler(handler)

    return logger