cpython/Lib/test/test_free_threading/test_gc.py
Sam Gross 3d4ac1a2c2
gh-123358: Use _PyStackRef in LOAD_DEREF (gh-130064)
Concurrent accesses from multiple threads to the same `cell` object did not
scale well in the free-threaded build. Use `_PyStackRef` and optimistically
avoid locking to improve scaling.

With the locks around cell reads gone, some of the free threading tests were
prone to starvation: the readers were able to run in a tight loop and the
writer threads weren't scheduled frequently enough to make timely progress.
Adjust the tests to avoid this.

Co-authored-by: Donghee Na <donghee.na@python.org>
2025-03-26 12:08:20 -04:00

67 lines
1.6 KiB
Python

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
if __name__ == "__main__":
unittest.main()