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gh-99578: Fix refleak in _imp.create_builtin() #99642

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Merged
merged 1 commit into from
Nov 21, 2022
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gh-99578: Fix refleak in _imp.create_builtin() #99642

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30 changes: 30 additions & 0 deletions Lib/test/test_imp.py
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
import gc
import importlib
import importlib.util
import os
Expand Down Expand Up @@ -413,6 +414,35 @@ def __init__(self, name):
bltin = create_builtin(spec)
self.assertEqual(bltin, builtins)

@support.cpython_only
def test_create_builtin_subinterp(self):
# gh-99578: create_builtin() behavior changes after the creation of the
# first sub-interpreter. Test both code paths, before and after the
# creation of a sub-interpreter. Previously, create_builtin() had
# a reference leak after the creation of the first sub-interpreter.

import builtins
create_builtin = support.get_attribute(_imp, "create_builtin")
class Spec:
name = "builtins"
spec = Spec()

def check_get_builtins():
refcnt = sys.getrefcount(builtins)
mod = _imp.create_builtin(spec)
self.assertIs(mod, builtins)
self.assertEqual(sys.getrefcount(builtins), refcnt + 1)
# Check that a GC collection doesn't crash
gc.collect()

check_get_builtins()

ret = support.run_in_subinterp("import builtins")
self.assertEqual(ret, 0)

check_get_builtins()


class ReloadTests(unittest.TestCase):

"""Very basic tests to make sure that imp.reload() operates just like
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2022-11-21-11-27-14.gh-issue-99578.DcKoBJ.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Fix a reference bug in :func:`_imp.create_builtin()` after the creation of the
first sub-interpreter for modules ``builtins`` and ``sys``. Patch by Victor
Stinner.
3 changes: 2 additions & 1 deletion Python/import.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1035,7 +1035,8 @@ create_builtin(PyThreadState *tstate, PyObject *name, PyObject *spec)
if (_PyUnicode_EqualToASCIIString(name, p->name)) {
if (p->initfunc == NULL) {
/* Cannot re-init internal module ("sys" or "builtins") */
return PyImport_AddModuleObject(name);
mod = PyImport_AddModuleObject(name);
return Py_XNewRef(mod);
}
mod = _PyImport_InitFunc_TrampolineCall(*p->initfunc);
if (mod == NULL) {
Expand Down