diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py index 94873ff6124d02..8f14ed30588810 100644 --- a/Lib/test/test_struct.py +++ b/Lib/test/test_struct.py @@ -1,10 +1,12 @@ from collections import abc import array +import gc import math import operator import unittest import struct import sys +import weakref from test import support from test.support import import_helper @@ -672,6 +674,21 @@ def __del__(self): self.assertIn(b"Exception ignored in:", stderr) self.assertIn(b"C.__del__", stderr) + def test__struct_reference_cycle_cleaned_up(self): + # Regression test for python/cpython#94207. + + # When we create a new struct module, trigger use of its cache, + # and then delete it ... + _struct_module = import_helper.import_fresh_module("_struct") + module_ref = weakref.ref(_struct_module) + _struct_module.calcsize("b") + del _struct_module + + # Then the module should have been garbage collected. + gc.collect() + self.assertIsNone( + module_ref(), "_struct module was not garbage collected") + def test_issue35714(self): # Embedded null characters should not be allowed in format strings. for s in '\0', '2\0i', b'\0': diff --git a/Misc/NEWS.d/next/Library/2022-06-24-19-23-59.gh-issue-94207.VhS1eS.rst b/Misc/NEWS.d/next/Library/2022-06-24-19-23-59.gh-issue-94207.VhS1eS.rst new file mode 100644 index 00000000000000..3d38524ac0e83c --- /dev/null +++ b/Misc/NEWS.d/next/Library/2022-06-24-19-23-59.gh-issue-94207.VhS1eS.rst @@ -0,0 +1,2 @@ +Made :class:`_struct.Struct` GC-tracked in order to fix a reference leak in +the :mod:`_struct` module. diff --git a/Modules/_struct.c b/Modules/_struct.c index 4daf9529d882c5..20307ad15be814 100644 --- a/Modules/_struct.c +++ b/Modules/_struct.c @@ -1496,10 +1496,26 @@ Struct___init___impl(PyStructObject *self, PyObject *format) return ret; } +static int +s_clear(PyStructObject *s) +{ + Py_CLEAR(s->s_format); + return 0; +} + +static int +s_traverse(PyStructObject *s, visitproc visit, void *arg) +{ + Py_VISIT(Py_TYPE(s)); + Py_VISIT(s->s_format); + return 0; +} + static void s_dealloc(PyStructObject *s) { PyTypeObject *tp = Py_TYPE(s); + PyObject_GC_UnTrack(s); if (s->weakreflist != NULL) PyObject_ClearWeakRefs((PyObject *)s); if (s->s_codes != NULL) { @@ -2078,13 +2094,15 @@ static PyType_Slot PyStructType_slots[] = { {Py_tp_getattro, PyObject_GenericGetAttr}, {Py_tp_setattro, PyObject_GenericSetAttr}, {Py_tp_doc, (void*)s__doc__}, + {Py_tp_traverse, s_traverse}, + {Py_tp_clear, s_clear}, {Py_tp_methods, s_methods}, {Py_tp_members, s_members}, {Py_tp_getset, s_getsetlist}, {Py_tp_init, Struct___init__}, {Py_tp_alloc, PyType_GenericAlloc}, {Py_tp_new, s_new}, - {Py_tp_free, PyObject_Del}, + {Py_tp_free, PyObject_GC_Del}, {0, 0}, }; @@ -2092,7 +2110,7 @@ static PyType_Spec PyStructType_spec = { "_struct.Struct", sizeof(PyStructObject), 0, - Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, + Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_BASETYPE, PyStructType_slots };