cpython/Lib/test/test_threading_local.py
Amaury Forgeot d'Arc b15bdf7f7a #Issue3088 in-progress: Race condition with instances of classes derived from threading.local:
When a thread touches such an object for the first time, a new thread-local __dict__ is created,
and the __init__ method is run.
But a thread switch can occur here; if the other thread touches the same object, it installs another
__dict__; when the first thread resumes, it updates the dictionary of the second...

This is the deep cause of the failures in test_multiprocessing involving "managers" objects.

Backport of r64601.
2008-07-01 20:59:49 +00:00

55 lines
1.5 KiB
Python

import unittest
from doctest import DocTestSuite
from test import test_support
class ThreadingLocalTest(unittest.TestCase):
def test_derived(self):
# Issue 3088: if there is a threads switch inside the __init__
# of a threading.local derived class, the per-thread dictionary
# is created but not correctly set on the object.
# The first member set may be bogus.
import threading
import time
class Local(threading.local):
def __init__(self):
time.sleep(0.01)
local = Local()
def f(i):
local.x = i
# Simply check that the variable is correctly set
self.assertEqual(local.x, i)
threads= []
for i in range(10):
t = threading.Thread(target=f, args=(i,))
t.start()
threads.append(t)
for t in threads:
t.join()
def test_main():
suite = DocTestSuite('_threading_local')
try:
from thread import _local
except ImportError:
pass
else:
import _threading_local
local_orig = _threading_local.local
def setUp(test):
_threading_local.local = _local
def tearDown(test):
_threading_local.local = local_orig
suite.addTest(DocTestSuite('_threading_local',
setUp=setUp, tearDown=tearDown)
)
suite.addTest(unittest.makeSuite(ThreadingLocalTest))
test_support.run_suite(suite)
if __name__ == '__main__':
test_main()