Description
Bug report
Documentation for sys.addaudithook
states "Hooks can then log the event [...]".
This works when I don't log, but instead print
:
sys.addaudithook(print)
id(0) # printed
However, nothing gets logged when I follow the suggestion to log, like:
sys.addaudithook(functools.partial(logging.warning, 'Audit hook %s %s'))
id(0) # NOT logged
The cause is that logging.Logger._log
(called by logging.warning
) tries to find the caller (to populate module
, lineno
, funcName
log format fields). For this, logging.Logger._log
itself then causes audit events, which again call the audit hook. That results in infinite recursion, i.e. a RecursionError
exception, which aborts the audit hook, and silences logging.
Workaround
By (temporarily) modifying logging._srcfile
, the attempt to find the caller is skipped (and the log format fields are instead populated as "unknown"), infinite recursion and exception are prevented, and logging does happen:
sys.addaudithook(functools.partial(logging.warning, 'Audit hook %s %s'))
logging._srcfile = None # prevent finding caller
id(0) # logged
This is existing functionality, only (?) documented in source (file logging.__init__
, line 188: "Setting _srcfile to None will prevent findCaller() from being called. This way, you can avoid the overhead of fetching caller information"). Though it works, the workaround is hard to find and not ideal.
Solutions
- Ideally,
logging
should not attempt to gather caller info in an audit hook (however, this requires tight coupling of thelogging
andsys
modules, so they understand each others' internals) - Equally user-friendly, audit events would not be generated within audit hooks (that risks incompleteness of auditing, but so does silencing logging)
- Less user-friendly, a keyword parameter (e.g.
find_caller: bool = True
) could be added to the signature of each log function,logging.Logger._log
can inspect it, and the documentation forsys.addaudithook
should recommend to usefind_caller=False
for logging in audit hooks
# logging.Logger._log
if logging._srcfile and find_caller:
...
# to use
sys.addaudithook(functools.partial(logging.warning, 'Audit hook %s %s', find_caller=False))
id(0) # logged
- At the minimum, the documentation for
sys.addaudithook
should recommend above workaround, i.e. temporarily setlogging._srcfile = None
def my_log(event, args):
save_srcfile = logging._srcfile
logging._srcfile = None
logging.warning('Audit hook %s %s', event, args)
logging._srcfile = save_srcfile
sys.addaudithook(my_log)
id(0) # logged
Environment
The above issue exists in all Python versions supporting sys.addaudithook
, i.e. 3.8, 3.9, 3.10, and 3.11.
I tested on 3.8.10, 3.9.13, 3.10.4, and 3.110rc2 on Windows 11 64 bit.
Metadata
Metadata
Assignees
Projects
Status