New submission from Sam Gross: In general, an a PyTypeObject that has Py_TPFLAGS_HAVE_GC set must call PyObject_GC_UnTrack() before it frees any PyObject* references it owns. The only reference to this requirement I found is in https://docs.python.org/3/c-api/gcsupport.html#c._PyObject_GC_TRACK.
This requirement should be documented in: 1. https://docs.python.org/3/c-api/typeobj.html#c.PyTypeObject.tp_dealloc 2. https://docs.python.org/3/extending/newtypes.html A call to PyObject_GC_UnTrack() should also be added to he official "noddy4" example. Currently, the example is incorrect and can crash if a referred-to object triggers a GC from it's destructor. See the following example which segfaults: https://github.com/colesbury/noddy It may be worthwhile to have _Py_Dealloc call PyObject_GC_UnTrack() if the PyTypeObject has Py_TPFLAGS_HAVE_GC set. Considering that the official Python extension example is missing the call, it seems likely that extension writers often forget to include it. ---------- assignee: docs@python components: Documentation, Extension Modules messages: 281146 nosy: colesbury, docs@python priority: normal severity: normal status: open title: Document that tp_dealloc handler must call PyObject_GC_UnTrack if Py_TPFLAGS_HAVE_GC is set versions: Python 3.5 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue28737> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
