If a logger is disabled (by setting it's disabled attribute to True), the check for this is done late in the dispatch of the logging event - during the handle() call - rather than isEnabledFor(), which would short-circuit some processing. So the check for logger.disabled should be moved to isEnabledFor().

Credit to Abhijit Gadgil for raising this:

https://stackoverflow.com/questions/50453121/logger-disabled-check-much-later-in-python-logging-module-whats-the-rationale

The check in handle() should remain, because there are some scenarios where handle is called directly (e.g. when receiving events over a socket and dispatching to handlers). So the change would just be to add an additional check in isEnabledFor().

New changeset 6e3ca645e71dd021fead5a70dc06d9b663612e3a by Vinay Sajip (Timo Furrer) in branch 'master':
bpo-33606: improve logging performance when logger is disabled (GH-7285)
https://github.com/python/cpython/commit/6e3ca645e71dd021fead5a70dc06d9b663612e3a