Any logger created before calling logging.config.dictCOnfig is not configured

W. Matthew Wilson matt at
Wed Mar 6 18:53:38 CET 2013

It seems like that any logger I create BEFORE calling
logging.config.dictConfig does not get configured.

Meanwhile, if I configure the logger like I always have, by just setting
handlers on root, everything works fine, including the loggers that were
created BEFORE I configure logging.

I make a lot of module-level log instances.

I wrote a simple script to show my problem.  Run it like:

    $ python code

and then

    $ python dict

and see how the logging output is different.



import argparse
import logging
import logging.config

log1 = logging.getLogger('scratch')

def configure_logging_with_dictConfig():

    d = {
        'formatters': {
            'consolefmt': {
                'format': '%(asctime)s %(levelname)-10s %(process)-6d
%(name)-24s %(lineno)-4d %(message)s'}},

        'handlers': {
            'console': {
                'class': 'logging.StreamHandler',
                'formatter': 'consolefmt',
                'level': 'DEBUG'}},

        'root': {
            'handlers': ['console'],
            'level': 'DEBUG'},

       'version': 1}


def configure_logging_with_code():

    # Set the logger to DEBUG.

    # Now write a custom formatter, so that we get all those different
    # things.
    f = logging.Formatter(
        '%(asctime)s '
        '%(levelname)-10s '
        '%(process)-6d '
        '%(filename)-24s '
        '%(lineno)-4d '
        '%(message)s '

    # Set up a stream handler for DEBUG stuff (and greater).
    sh = logging.StreamHandler()

def set_up_arguments():

    ap = argparse.ArgumentParser()
    ap.add_argument('how_to_configure', choices=['code', 'dict'])
    return ap.parse_args()

if __name__ == '__main__':

    args = set_up_arguments()

    if args.how_to_configure == 'code':

    elif args.how_to_configure == 'dict':

    log1.debug('debug from log1')

    # log2 is created AFTER I configure logging.
    log2 = logging.getLogger('log2')
    log2.debug('debug from log2')

    # Try to figure out what is the difference!  Nothing jumps out at me.

    print "log.root.level: {0}".format(log1.root.level)
    print "log.root.handlers: {0}".format(log1.root.handlers)

    print "log1.parent.level: {0}".format(log1.parent.level)
    print "log1.parent.handlers: {0}".format(log1.parent.handlers)

    print "log1.level: {0}".format(log1.level)
    print "log1.handlers: {0}".format(log1.handlers)
    print "log1.propagate: {0}".format(log1.propagate)
    print "log1.getEffectiveLevel(): {0}".format(log1.getEffectiveLevel())


W. Matthew Wilson
matt at
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