import logging
import logging.handlers

loggerA = logging.getLogger('loggerA')
loggerB = logging.getLogger('loggerB')

def setup_logger(logger):
    logger.setLevel('DEBUG')
    handler = logging.handlers.RotatingFileHandler(
        filename='test-issue25121.log',
        maxBytes=10*1000,   # 10KB
        backupCount=1,
        encoding='utf-8')
    handler.setLevel('DEBUG')
    logger.addHandler(handler)

setup_logger(loggerA)
setup_logger(loggerB)

i = 0
while True:
    i = i + 1
    loggerA.debug("%d times write this on the wall: I will never break standard logging library" % i)