On Mon, 1 Jun 2015 16:38:35 +0200 Petr Viktorin <encu...@gmail.com> wrote: > Hello, > The new test_importlib.extension.test_loader is currently leaking > references, (issue24268). There is a simple hack to stop this, but I'm > inclined to not apply quick hacks and rather dig into the root cause. > (It's a test module, the refleaks are relatively harmless.) > > The tests are based directly on the "xxlimited" example, > xxlimited.Xxo, which exhibits the same bug -- it's just not tested. > It's is caused by a combination of a few factors, but I'm not sure > what's a bug and what's just undocumented behavior, so I'm asking for > input to put me on the right track.
Yes, the issue is really nasty. There are several situations to take into account: - derived heap type inherits from base heap type, both have custom deallocs - derived heap type inherits from base heap type, only one has a custom dealloc - derived heap type inherits from Python-defined class (the latter having subtype_dealloc) - derived heap type inherits from static type - ... It is unreasonable to expect developers of C extensions come up with the correct incantation (and ideally, they shouldn't have to think about it at all). > The nice way out would be taking advantage of PEP 442: xxlimited.Xxo > can ditch tp_dealloc in favor of tp_traverse and tp_finalize (the > former of which it needs anyway to behave correctly). Unfortunately, > tp_finalize is not available in the stable ABI (issue24345). I think > it should be added; is it too late for 3.5? Well, but.... the stable ABI is supposed to be a subset of the API that's safe to program against, regardless of the Python version (at least from the point where the stable ABI was introduced). What happens if you define a Py_tp_finalize and run your C extension type on a pre-3.5 version? Do you get an error at definition time? A resource leak? A crash? I don't get why Benjamin committed the change so quick. Regards Antoine. _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
