1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
|
import unittest
import threading
from threading import Thread
from unittest import TestCase
import gc
from test.support import threading_helper
class MyObj:
pass
@threading_helper.requires_working_threading()
class TestGC(TestCase):
def test_get_objects(self):
event = threading.Event()
def gc_thread():
for i in range(100):
o = gc.get_objects()
event.set()
def mutator_thread():
while not event.is_set():
o1 = MyObj()
o2 = MyObj()
o3 = MyObj()
o4 = MyObj()
gcs = [Thread(target=gc_thread)]
mutators = [Thread(target=mutator_thread) for _ in range(4)]
with threading_helper.start_threads(gcs + mutators):
pass
def test_get_referrers(self):
NUM_GC = 2
NUM_MUTATORS = 4
b = threading.Barrier(NUM_GC + NUM_MUTATORS)
event = threading.Event()
obj = MyObj()
def gc_thread():
b.wait()
for i in range(100):
o = gc.get_referrers(obj)
event.set()
def mutator_thread():
b.wait()
while not event.is_set():
d1 = { "key": obj }
d2 = { "key": obj }
d3 = { "key": obj }
d4 = { "key": obj }
gcs = [Thread(target=gc_thread) for _ in range(NUM_GC)]
mutators = [Thread(target=mutator_thread) for _ in range(NUM_MUTATORS)]
with threading_helper.start_threads(gcs + mutators):
pass
def test_freeze_object_in_brc_queue(self):
# GH-142975: Freezing objects in the BRC queue could result in some
# objects having a zero refcount without being deallocated.
class Weird:
# We need a destructor to trigger the check for object resurrection
def __del__(self):
pass
# This is owned by the main thread, so the subthread will have to increment
# this object's reference count.
weird = Weird()
def evil():
gc.freeze()
# Decrement the reference count from this thread, which will trigger the
# slow path during resurrection and add our weird object to the BRC queue.
nonlocal weird
del weird
# Collection will merge the object's reference count and make it zero.
gc.collect()
# Unfreeze the object, making it visible to the GC.
gc.unfreeze()
gc.collect()
thread = Thread(target=evil)
thread.start()
thread.join()
if __name__ == "__main__":
unittest.main()
|
