python logging ensure a handler is added only once

Question

I have a piece of code that is initializing a logger as below.

logger = logging.getLogger()
hdlr = logging.FileHandler(\'logfile.log\')
formatter = logging.         


        

Answer 1

You can also just check to see whether the handler list is empty. Here's the solution I wound up with:

def setup_logging(self, logfile):
    self._logger = logging.getLogger('TestSuite')
    self._logger.setLevel(logging.INFO)
    host = socket.gethostname().split('.')[0]
    if self._logger.handlers == []:
        fh = logging.handlers.RotatingFileHandler(logfile,
                                                  maxBytes=10*1024*1024,
                                                  backupCount=5)
        strfmt = "%" + "(asctime)s [%s] " % host + "%" + "(message)s"
        fmt = logging.Formatter(strfmt, datefmt="%Y.%m%d %H:%M:%S")
        fh.setFormatter(fmt)

        self._logger.addHandler(fh)
    self._logger.info('-' * (55 - len(host)))

I was seeing the handler added multiple times, so each log message was getting written to the log file more than once, and this fixed it.