2017年11月16日 13:54 GMT+01:00 Antoine Pitrou <[email protected]>: > -Wdefault means -Wonce or -Walways? If the former, I don't expect many > warnings to be emitted.
It's kind of funny that passing "-W default" changes the "default" behaviour. "-W default" is documented as: "Explicitly request the default behavior (printing each warning once per source line)." https://docs.python.org/dev/using/cmdline.html#cmdoption-w Default warnings filters in release mode: $ python3 -c 'import pprint, warnings; pprint.pprint(warnings.filters)' [('ignore', None, <class 'DeprecationWarning'>, None, 0), ('ignore', None, <class 'PendingDeprecationWarning'>, None, 0), ('ignore', None, <class 'ImportWarning'>, None, 0), ('ignore', None, <class 'BytesWarning'>, None, 0), ('ignore', None, <class 'ResourceWarning'>, None, 0)] -Wd adds the a warnings filter with the "default" action matching all warnings (any kind, any message, any line number) if I understand correctly: $ python3 -Wd -c 'import pprint, warnings; pprint.pprint(warnings.filters)' [('default', re.compile('', re.IGNORECASE), <class 'Warning'>, re.compile(''), 0), ('ignore', None, <class 'DeprecationWarning'>, None, 0), ('ignore', None, <class 'PendingDeprecationWarning'>, None, 0), ('ignore', None, <class 'ImportWarning'>, None, 0), ('ignore', None, <class 'BytesWarning'>, None, 0), ('ignore', None, <class 'ResourceWarning'>, None, 0)] "default" and "once" actions are different: default: "print the first occurrence of matching warnings for **each location where the warning is issued**" once: "print only the first occurrence of matching warnings, **regardless of location**" >> For example, on test_os, PYTHONMALLOC=debug increases the peak memory >> usage from 10.5 MiB to 15.8 MiB: +50%. > > I see. For my use cases, this would be acceptable :-) > > But I think this should be documented, for example: > > """Currently, developer mode adds negligible CPU time overhead, but can > increase memory consumption significantly if many small objects are > allocated. This is subject to change in the future.""" +50% memory is inacceptable to develop on embedded devices, or more generally with low level. But in that case, you are can enable options enabled by -X dev manually, without PYTHONMALLOC=debug :-) Ok, I will document that, I like your proposed paragraph. Victor _______________________________________________ Python-Dev mailing list [email protected] https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com