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GH-135552: Make the GC clear weakrefs later (GH-136189)

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Fix a bug caused by the garbage collector clearing weakrefs too early.  The
weakrefs in the ``tp_subclasses`` dictionary are needed in order to correctly
invalidate type caches (for example, by calling ``PyType_Modified()``).
Clearing weakrefs before calling finalizers causes the caches to not be
correctly invalidated.  That can cause crashes since the caches can refer to
invalid objects.  Defer the clearing of weakrefs without callbacks until after
finalizers are executed.
This commit is contained in:
Neil Schemenauer 2025-08-07 16:32:17 -07:00 • committed by GitHub
parent deb385a143
commit 350c58ba4e
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GPG key ID: B5690EEEBB952194
9 changed files with 317 additions and 140 deletions
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22
Lib/test/test_io.py
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@ -808,7 +808,12 @@ def test_closefd_attr(self):
def test_garbage_collection(self):
# FileIO objects are collected, and collecting them flushes
# all data to disk.
with warnings_helper.check_warnings(('', ResourceWarning)):
#
# Note that using warnings_helper.check_warnings() will keep the
# file alive due to the `source` argument to warn(). So, use
# catch_warnings() instead.
with warnings.catch_warnings():
warnings.simplefilter("ignore", ResourceWarning)
f = self.FileIO(os_helper.TESTFN, "wb")
f.write(b"abcxxx")
f.f = f
@ -1809,7 +1814,11 @@ def test_garbage_collection(self):
# C BufferedReader objects are collected.
# The Python version has __del__, so it ends into gc.garbage instead
self.addCleanup(os_helper.unlink, os_helper.TESTFN)
with warnings_helper.check_warnings(('', ResourceWarning)):
# Note that using warnings_helper.check_warnings() will keep the
# file alive due to the `source` argument to warn(). So, use
# catch_warnings() instead.
with warnings.catch_warnings():
warnings.simplefilter("ignore", ResourceWarning)
rawio = self.FileIO(os_helper.TESTFN, "w+b")
f = self.tp(rawio)
f.f = f
@ -2158,7 +2167,11 @@ def test_garbage_collection(self):
# all data to disk.
# The Python version has __del__, so it ends into gc.garbage instead
self.addCleanup(os_helper.unlink, os_helper.TESTFN)
with warnings_helper.check_warnings(('', ResourceWarning)):
# Note that using warnings_helper.check_warnings() will keep the
# file alive due to the `source` argument to warn(). So, use
# catch_warnings() instead.
with warnings.catch_warnings():
warnings.simplefilter("ignore", ResourceWarning)
rawio = self.FileIO(os_helper.TESTFN, "w+b")
f = self.tp(rawio)
f.write(b"123xxx")
@ -4080,7 +4093,8 @@ def test_garbage_collection(self):
# C TextIOWrapper objects are collected, and collecting them flushes
# all data to disk.
# The Python version has __del__, so it ends in gc.garbage instead.
with warnings_helper.check_warnings(('', ResourceWarning)):
with warnings.catch_warnings():
warnings.simplefilter("ignore", ResourceWarning)
rawio = self.FileIO(os_helper.TESTFN, "wb")
b = self.BufferedWriter(rawio)
t = self.TextIOWrapper(b, encoding="ascii")