python logging does not work at all

Question

I am trying to use logging in my small python project. Following the tutorial, I added the code below to my code, but the message wan't logged to the file as it was supposed to.

import logging logging.basicConfig( filename = "a.log", filemode="w", level = logging.DEBUG) logging.error("Log initialization failed.")

There was no log file created in the pwd. (I have used the following code to print out the pwd, and I am sure I checked the right directory.) So I manually created the file and ran the code, but the message was still not logged.

print "argv: %r"%(sys.argv,) print "dirname(argv[0]): %s"%os.path.abspath(os.path.expanduser(os.path.dirname(sys.argv[0]))) print "pwd: %s"%os.path.abspath(os.path.expanduser(os.path.curdir))

Has someone any clue what I did wrong here? Thanks in advance.

When you say There was log file, do you mean there was no log file? — David Robinson
– David Robinson, Commented Mar 1, 2013 at 21:44
David: Yes, I meant there was no log file generated by the logging mechanism. (I am not sure if this is the supposed behavior though). — MYP
– MYP, Commented Mar 1, 2013 at 21:46
Martijn: I'm running: Python 2.7.3 (default, Apr 10 2012, 23:24:47) [MSC v.1500 64 bit (AMD64)] on Windows 7 (64 bit) — MYP
– MYP, Commented Mar 1, 2013 at 21:46
Are you sure the logging code actually happened (did you put it in a function, or something similar)? Did you try putting a print statement next to it? — David Robinson
– David Robinson, Commented Mar 1, 2013 at 21:48

Martijn Pieters · Accepted Answer · 2013-03-01 22:22:22Z

26

You called basicConfig() twice at least; the first time without a filename. Clear the handlers and try again:

logging.getLogger('').handlers = [] logging.basicConfig( filename = "a.log", filemode="w", level = logging.DEBUG)

answered Mar 1, 2013 at 22:22

Martijn Pieters

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2 Comments

andrew cooke Over a year ago

where are the other calls?

MYP Over a year ago

@andrew: I called logging.info before basicConfig, and I thought it was harmless, so I didn't include it in the code above. The [Python logging HowTo][1] has stated this clearly, but I missed it somehow: The call to basicConfig() should come before any calls to debug(), info() etc. As it’s intended as a one-off simple configuration facility, only the first call will actually do anything: subsequent calls are effectively no-ops. [1]: docs.python.org/2/howto/logging.html

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