You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
1416 lines
46 KiB
1416 lines
46 KiB
import unittest
|
|
import unittest.mock
|
|
from test.support import (verbose, refcount_test,
|
|
cpython_only)
|
|
from test.support.import_helper import import_module
|
|
from test.support.os_helper import temp_dir, TESTFN, unlink
|
|
from test.support.script_helper import assert_python_ok, make_script
|
|
from test.support import threading_helper
|
|
|
|
import gc
|
|
import sys
|
|
import sysconfig
|
|
import textwrap
|
|
import threading
|
|
import time
|
|
import weakref
|
|
|
|
try:
|
|
from _testcapi import with_tp_del
|
|
except ImportError:
|
|
def with_tp_del(cls):
|
|
class C(object):
|
|
def __new__(cls, *args, **kwargs):
|
|
raise TypeError('requires _testcapi.with_tp_del')
|
|
return C
|
|
|
|
try:
|
|
from _testcapi import ContainerNoGC
|
|
except ImportError:
|
|
ContainerNoGC = None
|
|
|
|
### Support code
|
|
###############################################################################
|
|
|
|
# Bug 1055820 has several tests of longstanding bugs involving weakrefs and
|
|
# cyclic gc.
|
|
|
|
# An instance of C1055820 has a self-loop, so becomes cyclic trash when
|
|
# unreachable.
|
|
class C1055820(object):
|
|
def __init__(self, i):
|
|
self.i = i
|
|
self.loop = self
|
|
|
|
class GC_Detector(object):
|
|
# Create an instance I. Then gc hasn't happened again so long as
|
|
# I.gc_happened is false.
|
|
|
|
def __init__(self):
|
|
self.gc_happened = False
|
|
|
|
def it_happened(ignored):
|
|
self.gc_happened = True
|
|
|
|
# Create a piece of cyclic trash that triggers it_happened when
|
|
# gc collects it.
|
|
self.wr = weakref.ref(C1055820(666), it_happened)
|
|
|
|
@with_tp_del
|
|
class Uncollectable(object):
|
|
"""Create a reference cycle with multiple __del__ methods.
|
|
|
|
An object in a reference cycle will never have zero references,
|
|
and so must be garbage collected. If one or more objects in the
|
|
cycle have __del__ methods, the gc refuses to guess an order,
|
|
and leaves the cycle uncollected."""
|
|
def __init__(self, partner=None):
|
|
if partner is None:
|
|
self.partner = Uncollectable(partner=self)
|
|
else:
|
|
self.partner = partner
|
|
def __tp_del__(self):
|
|
pass
|
|
|
|
if sysconfig.get_config_vars().get('PY_CFLAGS', ''):
|
|
BUILD_WITH_NDEBUG = ('-DNDEBUG' in sysconfig.get_config_vars()['PY_CFLAGS'])
|
|
else:
|
|
# Usually, sys.gettotalrefcount() is only present if Python has been
|
|
# compiled in debug mode. If it's missing, expect that Python has
|
|
# been released in release mode: with NDEBUG defined.
|
|
BUILD_WITH_NDEBUG = (not hasattr(sys, 'gettotalrefcount'))
|
|
|
|
### Tests
|
|
###############################################################################
|
|
|
|
class GCTests(unittest.TestCase):
|
|
def test_list(self):
|
|
l = []
|
|
l.append(l)
|
|
gc.collect()
|
|
del l
|
|
self.assertEqual(gc.collect(), 1)
|
|
|
|
def test_dict(self):
|
|
d = {}
|
|
d[1] = d
|
|
gc.collect()
|
|
del d
|
|
self.assertEqual(gc.collect(), 1)
|
|
|
|
def test_tuple(self):
|
|
# since tuples are immutable we close the loop with a list
|
|
l = []
|
|
t = (l,)
|
|
l.append(t)
|
|
gc.collect()
|
|
del t
|
|
del l
|
|
self.assertEqual(gc.collect(), 2)
|
|
|
|
def test_class(self):
|
|
class A:
|
|
pass
|
|
A.a = A
|
|
gc.collect()
|
|
del A
|
|
self.assertNotEqual(gc.collect(), 0)
|
|
|
|
def test_newstyleclass(self):
|
|
class A(object):
|
|
pass
|
|
gc.collect()
|
|
del A
|
|
self.assertNotEqual(gc.collect(), 0)
|
|
|
|
def test_instance(self):
|
|
class A:
|
|
pass
|
|
a = A()
|
|
a.a = a
|
|
gc.collect()
|
|
del a
|
|
self.assertNotEqual(gc.collect(), 0)
|
|
|
|
def test_newinstance(self):
|
|
class A(object):
|
|
pass
|
|
a = A()
|
|
a.a = a
|
|
gc.collect()
|
|
del a
|
|
self.assertNotEqual(gc.collect(), 0)
|
|
class B(list):
|
|
pass
|
|
class C(B, A):
|
|
pass
|
|
a = C()
|
|
a.a = a
|
|
gc.collect()
|
|
del a
|
|
self.assertNotEqual(gc.collect(), 0)
|
|
del B, C
|
|
self.assertNotEqual(gc.collect(), 0)
|
|
A.a = A()
|
|
del A
|
|
self.assertNotEqual(gc.collect(), 0)
|
|
self.assertEqual(gc.collect(), 0)
|
|
|
|
def test_method(self):
|
|
# Tricky: self.__init__ is a bound method, it references the instance.
|
|
class A:
|
|
def __init__(self):
|
|
self.init = self.__init__
|
|
a = A()
|
|
gc.collect()
|
|
del a
|
|
self.assertNotEqual(gc.collect(), 0)
|
|
|
|
@cpython_only
|
|
def test_legacy_finalizer(self):
|
|
# A() is uncollectable if it is part of a cycle, make sure it shows up
|
|
# in gc.garbage.
|
|
@with_tp_del
|
|
class A:
|
|
def __tp_del__(self): pass
|
|
class B:
|
|
pass
|
|
a = A()
|
|
a.a = a
|
|
id_a = id(a)
|
|
b = B()
|
|
b.b = b
|
|
gc.collect()
|
|
del a
|
|
del b
|
|
self.assertNotEqual(gc.collect(), 0)
|
|
for obj in gc.garbage:
|
|
if id(obj) == id_a:
|
|
del obj.a
|
|
break
|
|
else:
|
|
self.fail("didn't find obj in garbage (finalizer)")
|
|
gc.garbage.remove(obj)
|
|
|
|
@cpython_only
|
|
def test_legacy_finalizer_newclass(self):
|
|
# A() is uncollectable if it is part of a cycle, make sure it shows up
|
|
# in gc.garbage.
|
|
@with_tp_del
|
|
class A(object):
|
|
def __tp_del__(self): pass
|
|
class B(object):
|
|
pass
|
|
a = A()
|
|
a.a = a
|
|
id_a = id(a)
|
|
b = B()
|
|
b.b = b
|
|
gc.collect()
|
|
del a
|
|
del b
|
|
self.assertNotEqual(gc.collect(), 0)
|
|
for obj in gc.garbage:
|
|
if id(obj) == id_a:
|
|
del obj.a
|
|
break
|
|
else:
|
|
self.fail("didn't find obj in garbage (finalizer)")
|
|
gc.garbage.remove(obj)
|
|
|
|
def test_function(self):
|
|
# Tricky: f -> d -> f, code should call d.clear() after the exec to
|
|
# break the cycle.
|
|
d = {}
|
|
exec("def f(): pass\n", d)
|
|
gc.collect()
|
|
del d
|
|
self.assertEqual(gc.collect(), 2)
|
|
|
|
@refcount_test
|
|
def test_frame(self):
|
|
def f():
|
|
frame = sys._getframe()
|
|
gc.collect()
|
|
f()
|
|
self.assertEqual(gc.collect(), 1)
|
|
|
|
def test_saveall(self):
|
|
# Verify that cyclic garbage like lists show up in gc.garbage if the
|
|
# SAVEALL option is enabled.
|
|
|
|
# First make sure we don't save away other stuff that just happens to
|
|
# be waiting for collection.
|
|
gc.collect()
|
|
# if this fails, someone else created immortal trash
|
|
self.assertEqual(gc.garbage, [])
|
|
|
|
L = []
|
|
L.append(L)
|
|
id_L = id(L)
|
|
|
|
debug = gc.get_debug()
|
|
gc.set_debug(debug | gc.DEBUG_SAVEALL)
|
|
del L
|
|
gc.collect()
|
|
gc.set_debug(debug)
|
|
|
|
self.assertEqual(len(gc.garbage), 1)
|
|
obj = gc.garbage.pop()
|
|
self.assertEqual(id(obj), id_L)
|
|
|
|
def test_del(self):
|
|
# __del__ methods can trigger collection, make this to happen
|
|
thresholds = gc.get_threshold()
|
|
gc.enable()
|
|
gc.set_threshold(1)
|
|
|
|
class A:
|
|
def __del__(self):
|
|
dir(self)
|
|
a = A()
|
|
del a
|
|
|
|
gc.disable()
|
|
gc.set_threshold(*thresholds)
|
|
|
|
def test_del_newclass(self):
|
|
# __del__ methods can trigger collection, make this to happen
|
|
thresholds = gc.get_threshold()
|
|
gc.enable()
|
|
gc.set_threshold(1)
|
|
|
|
class A(object):
|
|
def __del__(self):
|
|
dir(self)
|
|
a = A()
|
|
del a
|
|
|
|
gc.disable()
|
|
gc.set_threshold(*thresholds)
|
|
|
|
# The following two tests are fragile:
|
|
# They precisely count the number of allocations,
|
|
# which is highly implementation-dependent.
|
|
# For example, disposed tuples are not freed, but reused.
|
|
# To minimize variations, though, we first store the get_count() results
|
|
# and check them at the end.
|
|
@refcount_test
|
|
def test_get_count(self):
|
|
gc.collect()
|
|
a, b, c = gc.get_count()
|
|
x = []
|
|
d, e, f = gc.get_count()
|
|
self.assertEqual((b, c), (0, 0))
|
|
self.assertEqual((e, f), (0, 0))
|
|
# This is less fragile than asserting that a equals 0.
|
|
self.assertLess(a, 5)
|
|
# Between the two calls to get_count(), at least one object was
|
|
# created (the list).
|
|
self.assertGreater(d, a)
|
|
|
|
@refcount_test
|
|
def test_collect_generations(self):
|
|
gc.collect()
|
|
# This object will "trickle" into generation N + 1 after
|
|
# each call to collect(N)
|
|
x = []
|
|
gc.collect(0)
|
|
# x is now in gen 1
|
|
a, b, c = gc.get_count()
|
|
gc.collect(1)
|
|
# x is now in gen 2
|
|
d, e, f = gc.get_count()
|
|
gc.collect(2)
|
|
# x is now in gen 3
|
|
g, h, i = gc.get_count()
|
|
# We don't check a, d, g since their exact values depends on
|
|
# internal implementation details of the interpreter.
|
|
self.assertEqual((b, c), (1, 0))
|
|
self.assertEqual((e, f), (0, 1))
|
|
self.assertEqual((h, i), (0, 0))
|
|
|
|
def test_trashcan(self):
|
|
class Ouch:
|
|
n = 0
|
|
def __del__(self):
|
|
Ouch.n = Ouch.n + 1
|
|
if Ouch.n % 17 == 0:
|
|
gc.collect()
|
|
|
|
# "trashcan" is a hack to prevent stack overflow when deallocating
|
|
# very deeply nested tuples etc. It works in part by abusing the
|
|
# type pointer and refcount fields, and that can yield horrible
|
|
# problems when gc tries to traverse the structures.
|
|
# If this test fails (as it does in 2.0, 2.1 and 2.2), it will
|
|
# most likely die via segfault.
|
|
|
|
# Note: In 2.3 the possibility for compiling without cyclic gc was
|
|
# removed, and that in turn allows the trashcan mechanism to work
|
|
# via much simpler means (e.g., it never abuses the type pointer or
|
|
# refcount fields anymore). Since it's much less likely to cause a
|
|
# problem now, the various constants in this expensive (we force a lot
|
|
# of full collections) test are cut back from the 2.2 version.
|
|
gc.enable()
|
|
N = 150
|
|
for count in range(2):
|
|
t = []
|
|
for i in range(N):
|
|
t = [t, Ouch()]
|
|
u = []
|
|
for i in range(N):
|
|
u = [u, Ouch()]
|
|
v = {}
|
|
for i in range(N):
|
|
v = {1: v, 2: Ouch()}
|
|
gc.disable()
|
|
|
|
def test_trashcan_threads(self):
|
|
# Issue #13992: trashcan mechanism should be thread-safe
|
|
NESTING = 60
|
|
N_THREADS = 2
|
|
|
|
def sleeper_gen():
|
|
"""A generator that releases the GIL when closed or dealloc'ed."""
|
|
try:
|
|
yield
|
|
finally:
|
|
time.sleep(0.000001)
|
|
|
|
class C(list):
|
|
# Appending to a list is atomic, which avoids the use of a lock.
|
|
inits = []
|
|
dels = []
|
|
def __init__(self, alist):
|
|
self[:] = alist
|
|
C.inits.append(None)
|
|
def __del__(self):
|
|
# This __del__ is called by subtype_dealloc().
|
|
C.dels.append(None)
|
|
# `g` will release the GIL when garbage-collected. This
|
|
# helps assert subtype_dealloc's behaviour when threads
|
|
# switch in the middle of it.
|
|
g = sleeper_gen()
|
|
next(g)
|
|
# Now that __del__ is finished, subtype_dealloc will proceed
|
|
# to call list_dealloc, which also uses the trashcan mechanism.
|
|
|
|
def make_nested():
|
|
"""Create a sufficiently nested container object so that the
|
|
trashcan mechanism is invoked when deallocating it."""
|
|
x = C([])
|
|
for i in range(NESTING):
|
|
x = [C([x])]
|
|
del x
|
|
|
|
def run_thread():
|
|
"""Exercise make_nested() in a loop."""
|
|
while not exit:
|
|
make_nested()
|
|
|
|
old_switchinterval = sys.getswitchinterval()
|
|
sys.setswitchinterval(1e-5)
|
|
try:
|
|
exit = []
|
|
threads = []
|
|
for i in range(N_THREADS):
|
|
t = threading.Thread(target=run_thread)
|
|
threads.append(t)
|
|
with threading_helper.start_threads(threads, lambda: exit.append(1)):
|
|
time.sleep(1.0)
|
|
finally:
|
|
sys.setswitchinterval(old_switchinterval)
|
|
gc.collect()
|
|
self.assertEqual(len(C.inits), len(C.dels))
|
|
|
|
def test_boom(self):
|
|
class Boom:
|
|
def __getattr__(self, someattribute):
|
|
del self.attr
|
|
raise AttributeError
|
|
|
|
a = Boom()
|
|
b = Boom()
|
|
a.attr = b
|
|
b.attr = a
|
|
|
|
gc.collect()
|
|
garbagelen = len(gc.garbage)
|
|
del a, b
|
|
# a<->b are in a trash cycle now. Collection will invoke
|
|
# Boom.__getattr__ (to see whether a and b have __del__ methods), and
|
|
# __getattr__ deletes the internal "attr" attributes as a side effect.
|
|
# That causes the trash cycle to get reclaimed via refcounts falling to
|
|
# 0, thus mutating the trash graph as a side effect of merely asking
|
|
# whether __del__ exists. This used to (before 2.3b1) crash Python.
|
|
# Now __getattr__ isn't called.
|
|
self.assertEqual(gc.collect(), 4)
|
|
self.assertEqual(len(gc.garbage), garbagelen)
|
|
|
|
def test_boom2(self):
|
|
class Boom2:
|
|
def __init__(self):
|
|
self.x = 0
|
|
|
|
def __getattr__(self, someattribute):
|
|
self.x += 1
|
|
if self.x > 1:
|
|
del self.attr
|
|
raise AttributeError
|
|
|
|
a = Boom2()
|
|
b = Boom2()
|
|
a.attr = b
|
|
b.attr = a
|
|
|
|
gc.collect()
|
|
garbagelen = len(gc.garbage)
|
|
del a, b
|
|
# Much like test_boom(), except that __getattr__ doesn't break the
|
|
# cycle until the second time gc checks for __del__. As of 2.3b1,
|
|
# there isn't a second time, so this simply cleans up the trash cycle.
|
|
# We expect a, b, a.__dict__ and b.__dict__ (4 objects) to get
|
|
# reclaimed this way.
|
|
self.assertEqual(gc.collect(), 4)
|
|
self.assertEqual(len(gc.garbage), garbagelen)
|
|
|
|
def test_boom_new(self):
|
|
# boom__new and boom2_new are exactly like boom and boom2, except use
|
|
# new-style classes.
|
|
|
|
class Boom_New(object):
|
|
def __getattr__(self, someattribute):
|
|
del self.attr
|
|
raise AttributeError
|
|
|
|
a = Boom_New()
|
|
b = Boom_New()
|
|
a.attr = b
|
|
b.attr = a
|
|
|
|
gc.collect()
|
|
garbagelen = len(gc.garbage)
|
|
del a, b
|
|
self.assertEqual(gc.collect(), 4)
|
|
self.assertEqual(len(gc.garbage), garbagelen)
|
|
|
|
def test_boom2_new(self):
|
|
class Boom2_New(object):
|
|
def __init__(self):
|
|
self.x = 0
|
|
|
|
def __getattr__(self, someattribute):
|
|
self.x += 1
|
|
if self.x > 1:
|
|
del self.attr
|
|
raise AttributeError
|
|
|
|
a = Boom2_New()
|
|
b = Boom2_New()
|
|
a.attr = b
|
|
b.attr = a
|
|
|
|
gc.collect()
|
|
garbagelen = len(gc.garbage)
|
|
del a, b
|
|
self.assertEqual(gc.collect(), 4)
|
|
self.assertEqual(len(gc.garbage), garbagelen)
|
|
|
|
def test_get_referents(self):
|
|
alist = [1, 3, 5]
|
|
got = gc.get_referents(alist)
|
|
got.sort()
|
|
self.assertEqual(got, alist)
|
|
|
|
atuple = tuple(alist)
|
|
got = gc.get_referents(atuple)
|
|
got.sort()
|
|
self.assertEqual(got, alist)
|
|
|
|
adict = {1: 3, 5: 7}
|
|
expected = [1, 3, 5, 7]
|
|
got = gc.get_referents(adict)
|
|
got.sort()
|
|
self.assertEqual(got, expected)
|
|
|
|
got = gc.get_referents([1, 2], {3: 4}, (0, 0, 0))
|
|
got.sort()
|
|
self.assertEqual(got, [0, 0] + list(range(5)))
|
|
|
|
self.assertEqual(gc.get_referents(1, 'a', 4j), [])
|
|
|
|
def test_is_tracked(self):
|
|
# Atomic built-in types are not tracked, user-defined objects and
|
|
# mutable containers are.
|
|
# NOTE: types with special optimizations (e.g. tuple) have tests
|
|
# in their own test files instead.
|
|
self.assertFalse(gc.is_tracked(None))
|
|
self.assertFalse(gc.is_tracked(1))
|
|
self.assertFalse(gc.is_tracked(1.0))
|
|
self.assertFalse(gc.is_tracked(1.0 + 5.0j))
|
|
self.assertFalse(gc.is_tracked(True))
|
|
self.assertFalse(gc.is_tracked(False))
|
|
self.assertFalse(gc.is_tracked(b"a"))
|
|
self.assertFalse(gc.is_tracked("a"))
|
|
self.assertFalse(gc.is_tracked(bytearray(b"a")))
|
|
self.assertFalse(gc.is_tracked(type))
|
|
self.assertFalse(gc.is_tracked(int))
|
|
self.assertFalse(gc.is_tracked(object))
|
|
self.assertFalse(gc.is_tracked(object()))
|
|
|
|
class UserClass:
|
|
pass
|
|
|
|
class UserInt(int):
|
|
pass
|
|
|
|
# Base class is object; no extra fields.
|
|
class UserClassSlots:
|
|
__slots__ = ()
|
|
|
|
# Base class is fixed size larger than object; no extra fields.
|
|
class UserFloatSlots(float):
|
|
__slots__ = ()
|
|
|
|
# Base class is variable size; no extra fields.
|
|
class UserIntSlots(int):
|
|
__slots__ = ()
|
|
|
|
self.assertTrue(gc.is_tracked(gc))
|
|
self.assertTrue(gc.is_tracked(UserClass))
|
|
self.assertTrue(gc.is_tracked(UserClass()))
|
|
self.assertTrue(gc.is_tracked(UserInt()))
|
|
self.assertTrue(gc.is_tracked([]))
|
|
self.assertTrue(gc.is_tracked(set()))
|
|
self.assertTrue(gc.is_tracked(UserClassSlots()))
|
|
self.assertTrue(gc.is_tracked(UserFloatSlots()))
|
|
self.assertTrue(gc.is_tracked(UserIntSlots()))
|
|
|
|
def test_is_finalized(self):
|
|
# Objects not tracked by the always gc return false
|
|
self.assertFalse(gc.is_finalized(3))
|
|
|
|
storage = []
|
|
class Lazarus:
|
|
def __del__(self):
|
|
storage.append(self)
|
|
|
|
lazarus = Lazarus()
|
|
self.assertFalse(gc.is_finalized(lazarus))
|
|
|
|
del lazarus
|
|
gc.collect()
|
|
|
|
lazarus = storage.pop()
|
|
self.assertTrue(gc.is_finalized(lazarus))
|
|
|
|
def test_bug1055820b(self):
|
|
# Corresponds to temp2b.py in the bug report.
|
|
|
|
ouch = []
|
|
def callback(ignored):
|
|
ouch[:] = [wr() for wr in WRs]
|
|
|
|
Cs = [C1055820(i) for i in range(2)]
|
|
WRs = [weakref.ref(c, callback) for c in Cs]
|
|
c = None
|
|
|
|
gc.collect()
|
|
self.assertEqual(len(ouch), 0)
|
|
# Make the two instances trash, and collect again. The bug was that
|
|
# the callback materialized a strong reference to an instance, but gc
|
|
# cleared the instance's dict anyway.
|
|
Cs = None
|
|
gc.collect()
|
|
self.assertEqual(len(ouch), 2) # else the callbacks didn't run
|
|
for x in ouch:
|
|
# If the callback resurrected one of these guys, the instance
|
|
# would be damaged, with an empty __dict__.
|
|
self.assertEqual(x, None)
|
|
|
|
def test_bug21435(self):
|
|
# This is a poor test - its only virtue is that it happened to
|
|
# segfault on Tim's Windows box before the patch for 21435 was
|
|
# applied. That's a nasty bug relying on specific pieces of cyclic
|
|
# trash appearing in exactly the right order in finalize_garbage()'s
|
|
# input list.
|
|
# But there's no reliable way to force that order from Python code,
|
|
# so over time chances are good this test won't really be testing much
|
|
# of anything anymore. Still, if it blows up, there's _some_
|
|
# problem ;-)
|
|
gc.collect()
|
|
|
|
class A:
|
|
pass
|
|
|
|
class B:
|
|
def __init__(self, x):
|
|
self.x = x
|
|
|
|
def __del__(self):
|
|
self.attr = None
|
|
|
|
def do_work():
|
|
a = A()
|
|
b = B(A())
|
|
|
|
a.attr = b
|
|
b.attr = a
|
|
|
|
do_work()
|
|
gc.collect() # this blows up (bad C pointer) when it fails
|
|
|
|
@cpython_only
|
|
def test_garbage_at_shutdown(self):
|
|
import subprocess
|
|
code = """if 1:
|
|
import gc
|
|
import _testcapi
|
|
@_testcapi.with_tp_del
|
|
class X:
|
|
def __init__(self, name):
|
|
self.name = name
|
|
def __repr__(self):
|
|
return "<X %%r>" %% self.name
|
|
def __tp_del__(self):
|
|
pass
|
|
|
|
x = X('first')
|
|
x.x = x
|
|
x.y = X('second')
|
|
del x
|
|
gc.set_debug(%s)
|
|
"""
|
|
def run_command(code):
|
|
p = subprocess.Popen([sys.executable, "-Wd", "-c", code],
|
|
stdout=subprocess.PIPE,
|
|
stderr=subprocess.PIPE)
|
|
stdout, stderr = p.communicate()
|
|
p.stdout.close()
|
|
p.stderr.close()
|
|
self.assertEqual(p.returncode, 0)
|
|
self.assertEqual(stdout, b"")
|
|
return stderr
|
|
|
|
stderr = run_command(code % "0")
|
|
self.assertIn(b"ResourceWarning: gc: 2 uncollectable objects at "
|
|
b"shutdown; use", stderr)
|
|
self.assertNotIn(b"<X 'first'>", stderr)
|
|
# With DEBUG_UNCOLLECTABLE, the garbage list gets printed
|
|
stderr = run_command(code % "gc.DEBUG_UNCOLLECTABLE")
|
|
self.assertIn(b"ResourceWarning: gc: 2 uncollectable objects at "
|
|
b"shutdown", stderr)
|
|
self.assertTrue(
|
|
(b"[<X 'first'>, <X 'second'>]" in stderr) or
|
|
(b"[<X 'second'>, <X 'first'>]" in stderr), stderr)
|
|
# With DEBUG_SAVEALL, no additional message should get printed
|
|
# (because gc.garbage also contains normally reclaimable cyclic
|
|
# references, and its elements get printed at runtime anyway).
|
|
stderr = run_command(code % "gc.DEBUG_SAVEALL")
|
|
self.assertNotIn(b"uncollectable objects at shutdown", stderr)
|
|
|
|
def test_gc_main_module_at_shutdown(self):
|
|
# Create a reference cycle through the __main__ module and check
|
|
# it gets collected at interpreter shutdown.
|
|
code = """if 1:
|
|
class C:
|
|
def __del__(self):
|
|
print('__del__ called')
|
|
l = [C()]
|
|
l.append(l)
|
|
"""
|
|
rc, out, err = assert_python_ok('-c', code)
|
|
self.assertEqual(out.strip(), b'__del__ called')
|
|
|
|
def test_gc_ordinary_module_at_shutdown(self):
|
|
# Same as above, but with a non-__main__ module.
|
|
with temp_dir() as script_dir:
|
|
module = """if 1:
|
|
class C:
|
|
def __del__(self):
|
|
print('__del__ called')
|
|
l = [C()]
|
|
l.append(l)
|
|
"""
|
|
code = """if 1:
|
|
import sys
|
|
sys.path.insert(0, %r)
|
|
import gctest
|
|
""" % (script_dir,)
|
|
make_script(script_dir, 'gctest', module)
|
|
rc, out, err = assert_python_ok('-c', code)
|
|
self.assertEqual(out.strip(), b'__del__ called')
|
|
|
|
def test_global_del_SystemExit(self):
|
|
code = """if 1:
|
|
class ClassWithDel:
|
|
def __del__(self):
|
|
print('__del__ called')
|
|
a = ClassWithDel()
|
|
a.link = a
|
|
raise SystemExit(0)"""
|
|
self.addCleanup(unlink, TESTFN)
|
|
with open(TESTFN, 'w', encoding="utf-8") as script:
|
|
script.write(code)
|
|
rc, out, err = assert_python_ok(TESTFN)
|
|
self.assertEqual(out.strip(), b'__del__ called')
|
|
|
|
def test_get_stats(self):
|
|
stats = gc.get_stats()
|
|
self.assertEqual(len(stats), 3)
|
|
for st in stats:
|
|
self.assertIsInstance(st, dict)
|
|
self.assertEqual(set(st),
|
|
{"collected", "collections", "uncollectable"})
|
|
self.assertGreaterEqual(st["collected"], 0)
|
|
self.assertGreaterEqual(st["collections"], 0)
|
|
self.assertGreaterEqual(st["uncollectable"], 0)
|
|
# Check that collection counts are incremented correctly
|
|
if gc.isenabled():
|
|
self.addCleanup(gc.enable)
|
|
gc.disable()
|
|
old = gc.get_stats()
|
|
gc.collect(0)
|
|
new = gc.get_stats()
|
|
self.assertEqual(new[0]["collections"], old[0]["collections"] + 1)
|
|
self.assertEqual(new[1]["collections"], old[1]["collections"])
|
|
self.assertEqual(new[2]["collections"], old[2]["collections"])
|
|
gc.collect(2)
|
|
new = gc.get_stats()
|
|
self.assertEqual(new[0]["collections"], old[0]["collections"] + 1)
|
|
self.assertEqual(new[1]["collections"], old[1]["collections"])
|
|
self.assertEqual(new[2]["collections"], old[2]["collections"] + 1)
|
|
|
|
def test_freeze(self):
|
|
gc.freeze()
|
|
self.assertGreater(gc.get_freeze_count(), 0)
|
|
gc.unfreeze()
|
|
self.assertEqual(gc.get_freeze_count(), 0)
|
|
|
|
def test_get_objects(self):
|
|
gc.collect()
|
|
l = []
|
|
l.append(l)
|
|
self.assertTrue(
|
|
any(l is element for element in gc.get_objects(generation=0))
|
|
)
|
|
self.assertFalse(
|
|
any(l is element for element in gc.get_objects(generation=1))
|
|
)
|
|
self.assertFalse(
|
|
any(l is element for element in gc.get_objects(generation=2))
|
|
)
|
|
gc.collect(generation=0)
|
|
self.assertFalse(
|
|
any(l is element for element in gc.get_objects(generation=0))
|
|
)
|
|
self.assertTrue(
|
|
any(l is element for element in gc.get_objects(generation=1))
|
|
)
|
|
self.assertFalse(
|
|
any(l is element for element in gc.get_objects(generation=2))
|
|
)
|
|
gc.collect(generation=1)
|
|
self.assertFalse(
|
|
any(l is element for element in gc.get_objects(generation=0))
|
|
)
|
|
self.assertFalse(
|
|
any(l is element for element in gc.get_objects(generation=1))
|
|
)
|
|
self.assertTrue(
|
|
any(l is element for element in gc.get_objects(generation=2))
|
|
)
|
|
gc.collect(generation=2)
|
|
self.assertFalse(
|
|
any(l is element for element in gc.get_objects(generation=0))
|
|
)
|
|
self.assertFalse(
|
|
any(l is element for element in gc.get_objects(generation=1))
|
|
)
|
|
self.assertTrue(
|
|
any(l is element for element in gc.get_objects(generation=2))
|
|
)
|
|
del l
|
|
gc.collect()
|
|
|
|
def test_get_objects_arguments(self):
|
|
gc.collect()
|
|
self.assertEqual(len(gc.get_objects()),
|
|
len(gc.get_objects(generation=None)))
|
|
|
|
self.assertRaises(ValueError, gc.get_objects, 1000)
|
|
self.assertRaises(ValueError, gc.get_objects, -1000)
|
|
self.assertRaises(TypeError, gc.get_objects, "1")
|
|
self.assertRaises(TypeError, gc.get_objects, 1.234)
|
|
|
|
def test_resurrection_only_happens_once_per_object(self):
|
|
class A: # simple self-loop
|
|
def __init__(self):
|
|
self.me = self
|
|
|
|
class Lazarus(A):
|
|
resurrected = 0
|
|
resurrected_instances = []
|
|
|
|
def __del__(self):
|
|
Lazarus.resurrected += 1
|
|
Lazarus.resurrected_instances.append(self)
|
|
|
|
gc.collect()
|
|
gc.disable()
|
|
|
|
# We start with 0 resurrections
|
|
laz = Lazarus()
|
|
self.assertEqual(Lazarus.resurrected, 0)
|
|
|
|
# Deleting the instance and triggering a collection
|
|
# resurrects the object
|
|
del laz
|
|
gc.collect()
|
|
self.assertEqual(Lazarus.resurrected, 1)
|
|
self.assertEqual(len(Lazarus.resurrected_instances), 1)
|
|
|
|
# Clearing the references and forcing a collection
|
|
# should not resurrect the object again.
|
|
Lazarus.resurrected_instances.clear()
|
|
self.assertEqual(Lazarus.resurrected, 1)
|
|
gc.collect()
|
|
self.assertEqual(Lazarus.resurrected, 1)
|
|
|
|
gc.enable()
|
|
|
|
def test_resurrection_is_transitive(self):
|
|
class Cargo:
|
|
def __init__(self):
|
|
self.me = self
|
|
|
|
class Lazarus:
|
|
resurrected_instances = []
|
|
|
|
def __del__(self):
|
|
Lazarus.resurrected_instances.append(self)
|
|
|
|
gc.collect()
|
|
gc.disable()
|
|
|
|
laz = Lazarus()
|
|
cargo = Cargo()
|
|
cargo_id = id(cargo)
|
|
|
|
# Create a cycle between cargo and laz
|
|
laz.cargo = cargo
|
|
cargo.laz = laz
|
|
|
|
# Drop the references, force a collection and check that
|
|
# everything was resurrected.
|
|
del laz, cargo
|
|
gc.collect()
|
|
self.assertEqual(len(Lazarus.resurrected_instances), 1)
|
|
instance = Lazarus.resurrected_instances.pop()
|
|
self.assertTrue(hasattr(instance, "cargo"))
|
|
self.assertEqual(id(instance.cargo), cargo_id)
|
|
|
|
gc.collect()
|
|
gc.enable()
|
|
|
|
def test_resurrection_does_not_block_cleanup_of_other_objects(self):
|
|
|
|
# When a finalizer resurrects objects, stats were reporting them as
|
|
# having been collected. This affected both collect()'s return
|
|
# value and the dicts returned by get_stats().
|
|
N = 100
|
|
|
|
class A: # simple self-loop
|
|
def __init__(self):
|
|
self.me = self
|
|
|
|
class Z(A): # resurrecting __del__
|
|
def __del__(self):
|
|
zs.append(self)
|
|
|
|
zs = []
|
|
|
|
def getstats():
|
|
d = gc.get_stats()[-1]
|
|
return d['collected'], d['uncollectable']
|
|
|
|
gc.collect()
|
|
gc.disable()
|
|
|
|
# No problems if just collecting A() instances.
|
|
oldc, oldnc = getstats()
|
|
for i in range(N):
|
|
A()
|
|
t = gc.collect()
|
|
c, nc = getstats()
|
|
self.assertEqual(t, 2*N) # instance object & its dict
|
|
self.assertEqual(c - oldc, 2*N)
|
|
self.assertEqual(nc - oldnc, 0)
|
|
|
|
# But Z() is not actually collected.
|
|
oldc, oldnc = c, nc
|
|
Z()
|
|
# Nothing is collected - Z() is merely resurrected.
|
|
t = gc.collect()
|
|
c, nc = getstats()
|
|
self.assertEqual(t, 0)
|
|
self.assertEqual(c - oldc, 0)
|
|
self.assertEqual(nc - oldnc, 0)
|
|
|
|
# Z() should not prevent anything else from being collected.
|
|
oldc, oldnc = c, nc
|
|
for i in range(N):
|
|
A()
|
|
Z()
|
|
t = gc.collect()
|
|
c, nc = getstats()
|
|
self.assertEqual(t, 2*N)
|
|
self.assertEqual(c - oldc, 2*N)
|
|
self.assertEqual(nc - oldnc, 0)
|
|
|
|
# The A() trash should have been reclaimed already but the
|
|
# 2 copies of Z are still in zs (and the associated dicts).
|
|
oldc, oldnc = c, nc
|
|
zs.clear()
|
|
t = gc.collect()
|
|
c, nc = getstats()
|
|
self.assertEqual(t, 4)
|
|
self.assertEqual(c - oldc, 4)
|
|
self.assertEqual(nc - oldnc, 0)
|
|
|
|
gc.enable()
|
|
|
|
@unittest.skipIf(ContainerNoGC is None,
|
|
'requires ContainerNoGC extension type')
|
|
def test_trash_weakref_clear(self):
|
|
# Test that trash weakrefs are properly cleared (bpo-38006).
|
|
#
|
|
# Structure we are creating:
|
|
#
|
|
# Z <- Y <- A--+--> WZ -> C
|
|
# ^ |
|
|
# +--+
|
|
# where:
|
|
# WZ is a weakref to Z with callback C
|
|
# Y doesn't implement tp_traverse
|
|
# A contains a reference to itself, Y and WZ
|
|
#
|
|
# A, Y, Z, WZ are all trash. The GC doesn't know that Z is trash
|
|
# because Y does not implement tp_traverse. To show the bug, WZ needs
|
|
# to live long enough so that Z is deallocated before it. Then, if
|
|
# gcmodule is buggy, when Z is being deallocated, C will run.
|
|
#
|
|
# To ensure WZ lives long enough, we put it in a second reference
|
|
# cycle. That trick only works due to the ordering of the GC prev/next
|
|
# linked lists. So, this test is a bit fragile.
|
|
#
|
|
# The bug reported in bpo-38006 is caused because the GC did not
|
|
# clear WZ before starting the process of calling tp_clear on the
|
|
# trash. Normally, handle_weakrefs() would find the weakref via Z and
|
|
# clear it. However, since the GC cannot find Z, WR is not cleared and
|
|
# it can execute during delete_garbage(). That can lead to disaster
|
|
# since the callback might tinker with objects that have already had
|
|
# tp_clear called on them (leaving them in possibly invalid states).
|
|
|
|
callback = unittest.mock.Mock()
|
|
|
|
class A:
|
|
__slots__ = ['a', 'y', 'wz']
|
|
|
|
class Z:
|
|
pass
|
|
|
|
# setup required object graph, as described above
|
|
a = A()
|
|
a.a = a
|
|
a.y = ContainerNoGC(Z())
|
|
a.wz = weakref.ref(a.y.value, callback)
|
|
# create second cycle to keep WZ alive longer
|
|
wr_cycle = [a.wz]
|
|
wr_cycle.append(wr_cycle)
|
|
# ensure trash unrelated to this test is gone
|
|
gc.collect()
|
|
gc.disable()
|
|
# release references and create trash
|
|
del a, wr_cycle
|
|
gc.collect()
|
|
# if called, it means there is a bug in the GC. The weakref should be
|
|
# cleared before Z dies.
|
|
callback.assert_not_called()
|
|
gc.enable()
|
|
|
|
|
|
class GCCallbackTests(unittest.TestCase):
|
|
def setUp(self):
|
|
# Save gc state and disable it.
|
|
self.enabled = gc.isenabled()
|
|
gc.disable()
|
|
self.debug = gc.get_debug()
|
|
gc.set_debug(0)
|
|
gc.callbacks.append(self.cb1)
|
|
gc.callbacks.append(self.cb2)
|
|
self.othergarbage = []
|
|
|
|
def tearDown(self):
|
|
# Restore gc state
|
|
del self.visit
|
|
gc.callbacks.remove(self.cb1)
|
|
gc.callbacks.remove(self.cb2)
|
|
gc.set_debug(self.debug)
|
|
if self.enabled:
|
|
gc.enable()
|
|
# destroy any uncollectables
|
|
gc.collect()
|
|
for obj in gc.garbage:
|
|
if isinstance(obj, Uncollectable):
|
|
obj.partner = None
|
|
del gc.garbage[:]
|
|
del self.othergarbage
|
|
gc.collect()
|
|
|
|
def preclean(self):
|
|
# Remove all fluff from the system. Invoke this function
|
|
# manually rather than through self.setUp() for maximum
|
|
# safety.
|
|
self.visit = []
|
|
gc.collect()
|
|
garbage, gc.garbage[:] = gc.garbage[:], []
|
|
self.othergarbage.append(garbage)
|
|
self.visit = []
|
|
|
|
def cb1(self, phase, info):
|
|
self.visit.append((1, phase, dict(info)))
|
|
|
|
def cb2(self, phase, info):
|
|
self.visit.append((2, phase, dict(info)))
|
|
if phase == "stop" and hasattr(self, "cleanup"):
|
|
# Clean Uncollectable from garbage
|
|
uc = [e for e in gc.garbage if isinstance(e, Uncollectable)]
|
|
gc.garbage[:] = [e for e in gc.garbage
|
|
if not isinstance(e, Uncollectable)]
|
|
for e in uc:
|
|
e.partner = None
|
|
|
|
def test_collect(self):
|
|
self.preclean()
|
|
gc.collect()
|
|
# Algorithmically verify the contents of self.visit
|
|
# because it is long and tortuous.
|
|
|
|
# Count the number of visits to each callback
|
|
n = [v[0] for v in self.visit]
|
|
n1 = [i for i in n if i == 1]
|
|
n2 = [i for i in n if i == 2]
|
|
self.assertEqual(n1, [1]*2)
|
|
self.assertEqual(n2, [2]*2)
|
|
|
|
# Count that we got the right number of start and stop callbacks.
|
|
n = [v[1] for v in self.visit]
|
|
n1 = [i for i in n if i == "start"]
|
|
n2 = [i for i in n if i == "stop"]
|
|
self.assertEqual(n1, ["start"]*2)
|
|
self.assertEqual(n2, ["stop"]*2)
|
|
|
|
# Check that we got the right info dict for all callbacks
|
|
for v in self.visit:
|
|
info = v[2]
|
|
self.assertTrue("generation" in info)
|
|
self.assertTrue("collected" in info)
|
|
self.assertTrue("uncollectable" in info)
|
|
|
|
def test_collect_generation(self):
|
|
self.preclean()
|
|
gc.collect(2)
|
|
for v in self.visit:
|
|
info = v[2]
|
|
self.assertEqual(info["generation"], 2)
|
|
|
|
@cpython_only
|
|
def test_collect_garbage(self):
|
|
self.preclean()
|
|
# Each of these cause four objects to be garbage: Two
|
|
# Uncollectables and their instance dicts.
|
|
Uncollectable()
|
|
Uncollectable()
|
|
C1055820(666)
|
|
gc.collect()
|
|
for v in self.visit:
|
|
if v[1] != "stop":
|
|
continue
|
|
info = v[2]
|
|
self.assertEqual(info["collected"], 2)
|
|
self.assertEqual(info["uncollectable"], 8)
|
|
|
|
# We should now have the Uncollectables in gc.garbage
|
|
self.assertEqual(len(gc.garbage), 4)
|
|
for e in gc.garbage:
|
|
self.assertIsInstance(e, Uncollectable)
|
|
|
|
# Now, let our callback handle the Uncollectable instances
|
|
self.cleanup=True
|
|
self.visit = []
|
|
gc.garbage[:] = []
|
|
gc.collect()
|
|
for v in self.visit:
|
|
if v[1] != "stop":
|
|
continue
|
|
info = v[2]
|
|
self.assertEqual(info["collected"], 0)
|
|
self.assertEqual(info["uncollectable"], 4)
|
|
|
|
# Uncollectables should be gone
|
|
self.assertEqual(len(gc.garbage), 0)
|
|
|
|
|
|
@unittest.skipIf(BUILD_WITH_NDEBUG,
|
|
'built with -NDEBUG')
|
|
def test_refcount_errors(self):
|
|
self.preclean()
|
|
# Verify the "handling" of objects with broken refcounts
|
|
|
|
# Skip the test if ctypes is not available
|
|
import_module("ctypes")
|
|
|
|
import subprocess
|
|
code = textwrap.dedent('''
|
|
from test.support import gc_collect, SuppressCrashReport
|
|
|
|
a = [1, 2, 3]
|
|
b = [a]
|
|
|
|
# Avoid coredump when Py_FatalError() calls abort()
|
|
SuppressCrashReport().__enter__()
|
|
|
|
# Simulate the refcount of "a" being too low (compared to the
|
|
# references held on it by live data), but keeping it above zero
|
|
# (to avoid deallocating it):
|
|
import ctypes
|
|
ctypes.pythonapi.Py_DecRef(ctypes.py_object(a))
|
|
|
|
# The garbage collector should now have a fatal error
|
|
# when it reaches the broken object
|
|
gc_collect()
|
|
''')
|
|
p = subprocess.Popen([sys.executable, "-c", code],
|
|
stdout=subprocess.PIPE,
|
|
stderr=subprocess.PIPE)
|
|
stdout, stderr = p.communicate()
|
|
p.stdout.close()
|
|
p.stderr.close()
|
|
# Verify that stderr has a useful error message:
|
|
self.assertRegex(stderr,
|
|
br'gcmodule\.c:[0-9]+: gc_decref: Assertion "gc_get_refs\(g\) > 0" failed.')
|
|
self.assertRegex(stderr,
|
|
br'refcount is too small')
|
|
# "address : 0x7fb5062efc18"
|
|
# "address : 7FB5062EFC18"
|
|
address_regex = br'[0-9a-fA-Fx]+'
|
|
self.assertRegex(stderr,
|
|
br'object address : ' + address_regex)
|
|
self.assertRegex(stderr,
|
|
br'object refcount : 1')
|
|
self.assertRegex(stderr,
|
|
br'object type : ' + address_regex)
|
|
self.assertRegex(stderr,
|
|
br'object type name: list')
|
|
self.assertRegex(stderr,
|
|
br'object repr : \[1, 2, 3\]')
|
|
|
|
|
|
class GCTogglingTests(unittest.TestCase):
|
|
def setUp(self):
|
|
gc.enable()
|
|
|
|
def tearDown(self):
|
|
gc.disable()
|
|
|
|
def test_bug1055820c(self):
|
|
# Corresponds to temp2c.py in the bug report. This is pretty
|
|
# elaborate.
|
|
|
|
c0 = C1055820(0)
|
|
# Move c0 into generation 2.
|
|
gc.collect()
|
|
|
|
c1 = C1055820(1)
|
|
c1.keep_c0_alive = c0
|
|
del c0.loop # now only c1 keeps c0 alive
|
|
|
|
c2 = C1055820(2)
|
|
c2wr = weakref.ref(c2) # no callback!
|
|
|
|
ouch = []
|
|
def callback(ignored):
|
|
ouch[:] = [c2wr()]
|
|
|
|
# The callback gets associated with a wr on an object in generation 2.
|
|
c0wr = weakref.ref(c0, callback)
|
|
|
|
c0 = c1 = c2 = None
|
|
|
|
# What we've set up: c0, c1, and c2 are all trash now. c0 is in
|
|
# generation 2. The only thing keeping it alive is that c1 points to
|
|
# it. c1 and c2 are in generation 0, and are in self-loops. There's a
|
|
# global weakref to c2 (c2wr), but that weakref has no callback.
|
|
# There's also a global weakref to c0 (c0wr), and that does have a
|
|
# callback, and that callback references c2 via c2wr().
|
|
#
|
|
# c0 has a wr with callback, which references c2wr
|
|
# ^
|
|
# |
|
|
# | Generation 2 above dots
|
|
#. . . . . . . .|. . . . . . . . . . . . . . . . . . . . . . . .
|
|
# | Generation 0 below dots
|
|
# |
|
|
# |
|
|
# ^->c1 ^->c2 has a wr but no callback
|
|
# | | | |
|
|
# <--v <--v
|
|
#
|
|
# So this is the nightmare: when generation 0 gets collected, we see
|
|
# that c2 has a callback-free weakref, and c1 doesn't even have a
|
|
# weakref. Collecting generation 0 doesn't see c0 at all, and c0 is
|
|
# the only object that has a weakref with a callback. gc clears c1
|
|
# and c2. Clearing c1 has the side effect of dropping the refcount on
|
|
# c0 to 0, so c0 goes away (despite that it's in an older generation)
|
|
# and c0's wr callback triggers. That in turn materializes a reference
|
|
# to c2 via c2wr(), but c2 gets cleared anyway by gc.
|
|
|
|
# We want to let gc happen "naturally", to preserve the distinction
|
|
# between generations.
|
|
junk = []
|
|
i = 0
|
|
detector = GC_Detector()
|
|
while not detector.gc_happened:
|
|
i += 1
|
|
if i > 10000:
|
|
self.fail("gc didn't happen after 10000 iterations")
|
|
self.assertEqual(len(ouch), 0)
|
|
junk.append([]) # this will eventually trigger gc
|
|
|
|
self.assertEqual(len(ouch), 1) # else the callback wasn't invoked
|
|
for x in ouch:
|
|
# If the callback resurrected c2, the instance would be damaged,
|
|
# with an empty __dict__.
|
|
self.assertEqual(x, None)
|
|
|
|
def test_bug1055820d(self):
|
|
# Corresponds to temp2d.py in the bug report. This is very much like
|
|
# test_bug1055820c, but uses a __del__ method instead of a weakref
|
|
# callback to sneak in a resurrection of cyclic trash.
|
|
|
|
ouch = []
|
|
class D(C1055820):
|
|
def __del__(self):
|
|
ouch[:] = [c2wr()]
|
|
|
|
d0 = D(0)
|
|
# Move all the above into generation 2.
|
|
gc.collect()
|
|
|
|
c1 = C1055820(1)
|
|
c1.keep_d0_alive = d0
|
|
del d0.loop # now only c1 keeps d0 alive
|
|
|
|
c2 = C1055820(2)
|
|
c2wr = weakref.ref(c2) # no callback!
|
|
|
|
d0 = c1 = c2 = None
|
|
|
|
# What we've set up: d0, c1, and c2 are all trash now. d0 is in
|
|
# generation 2. The only thing keeping it alive is that c1 points to
|
|
# it. c1 and c2 are in generation 0, and are in self-loops. There's
|
|
# a global weakref to c2 (c2wr), but that weakref has no callback.
|
|
# There are no other weakrefs.
|
|
#
|
|
# d0 has a __del__ method that references c2wr
|
|
# ^
|
|
# |
|
|
# | Generation 2 above dots
|
|
#. . . . . . . .|. . . . . . . . . . . . . . . . . . . . . . . .
|
|
# | Generation 0 below dots
|
|
# |
|
|
# |
|
|
# ^->c1 ^->c2 has a wr but no callback
|
|
# | | | |
|
|
# <--v <--v
|
|
#
|
|
# So this is the nightmare: when generation 0 gets collected, we see
|
|
# that c2 has a callback-free weakref, and c1 doesn't even have a
|
|
# weakref. Collecting generation 0 doesn't see d0 at all. gc clears
|
|
# c1 and c2. Clearing c1 has the side effect of dropping the refcount
|
|
# on d0 to 0, so d0 goes away (despite that it's in an older
|
|
# generation) and d0's __del__ triggers. That in turn materializes
|
|
# a reference to c2 via c2wr(), but c2 gets cleared anyway by gc.
|
|
|
|
# We want to let gc happen "naturally", to preserve the distinction
|
|
# between generations.
|
|
detector = GC_Detector()
|
|
junk = []
|
|
i = 0
|
|
while not detector.gc_happened:
|
|
i += 1
|
|
if i > 10000:
|
|
self.fail("gc didn't happen after 10000 iterations")
|
|
self.assertEqual(len(ouch), 0)
|
|
junk.append([]) # this will eventually trigger gc
|
|
|
|
self.assertEqual(len(ouch), 1) # else __del__ wasn't invoked
|
|
for x in ouch:
|
|
# If __del__ resurrected c2, the instance would be damaged, with an
|
|
# empty __dict__.
|
|
self.assertEqual(x, None)
|
|
|
|
|
|
class PythonFinalizationTests(unittest.TestCase):
|
|
def test_ast_fini(self):
|
|
# bpo-44184: Regression test for subtype_dealloc() when deallocating
|
|
# an AST instance also destroy its AST type: subtype_dealloc() must
|
|
# not access the type memory after deallocating the instance, since
|
|
# the type memory can be freed as well. The test is also related to
|
|
# _PyAST_Fini() which clears references to AST types.
|
|
code = textwrap.dedent("""
|
|
import ast
|
|
import codecs
|
|
|
|
# Small AST tree to keep their AST types alive
|
|
tree = ast.parse("def f(x, y): return 2*x-y")
|
|
x = [tree]
|
|
x.append(x)
|
|
|
|
# Put the cycle somewhere to survive until the last GC collection.
|
|
# Codec search functions are only cleared at the end of
|
|
# interpreter_clear().
|
|
def search_func(encoding):
|
|
return None
|
|
search_func.a = x
|
|
codecs.register(search_func)
|
|
""")
|
|
assert_python_ok("-c", code)
|
|
|
|
|
|
def setUpModule():
|
|
global enabled, debug
|
|
enabled = gc.isenabled()
|
|
gc.disable()
|
|
assert not gc.isenabled()
|
|
debug = gc.get_debug()
|
|
gc.set_debug(debug & ~gc.DEBUG_LEAK) # this test is supposed to leak
|
|
gc.collect() # Delete 2nd generation garbage
|
|
|
|
|
|
def tearDownModule():
|
|
gc.set_debug(debug)
|
|
# test gc.enable() even if GC is disabled by default
|
|
if verbose:
|
|
print("restoring automatic collection")
|
|
# make sure to always test gc.enable()
|
|
gc.enable()
|
|
assert gc.isenabled()
|
|
if not enabled:
|
|
gc.disable()
|
|
|
|
|
|
if __name__ == "__main__":
|
|
unittest.main()
|