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svn+ssh://pythondev@svn.python.org/python/trunk ........ r64601 | amaury.forgeotdarc | 2008-06-30 17:42:40 -0500 (Mon, 30 Jun 2008) | 11 lines #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. Also a 2.5 backport candidate. ........
94 lines
2.6 KiB
Python
94 lines
2.6 KiB
Python
import unittest
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from doctest import DocTestSuite
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from test import support
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import threading
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import weakref
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import gc
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class Weak(object):
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pass
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def target(local, weaklist):
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weak = Weak()
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local.weak = weak
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weaklist.append(weakref.ref(weak))
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class ThreadingLocalTest(unittest.TestCase):
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def test_local_refs(self):
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self._local_refs(20)
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self._local_refs(50)
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self._local_refs(100)
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def _local_refs(self, n):
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local = threading.local()
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weaklist = []
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for i in range(n):
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t = threading.Thread(target=target, args=(local, weaklist))
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t.start()
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t.join()
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del t
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gc.collect()
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self.assertEqual(len(weaklist), n)
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# XXX threading.local keeps the local of the last stopped thread alive.
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deadlist = [weak for weak in weaklist if weak() is None]
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self.assertEqual(len(deadlist), n-1)
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# Assignment to the same thread local frees it sometimes (!)
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local.someothervar = None
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gc.collect()
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deadlist = [weak for weak in weaklist if weak() is None]
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self.assert_(len(deadlist) in (n-1, n), (n, len(deadlist)))
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def test_derived(self):
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# Issue 3088: if there is a threads switch inside the __init__
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# of a threading.local derived class, the per-thread dictionary
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# is created but not correctly set on the object.
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# The first member set may be bogus.
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import time
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class Local(threading.local):
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def __init__(self):
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time.sleep(0.01)
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local = Local()
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def f(i):
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local.x = i
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# Simply check that the variable is correctly set
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self.assertEqual(local.x, i)
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threads= []
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for i in range(10):
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t = threading.Thread(target=f, args=(i,))
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t.start()
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threads.append(t)
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for t in threads:
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t.join()
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def test_main():
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suite = unittest.TestSuite()
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suite.addTest(DocTestSuite('_threading_local'))
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suite.addTest(unittest.makeSuite(ThreadingLocalTest))
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try:
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from thread import _local
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except ImportError:
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pass
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else:
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import _threading_local
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local_orig = _threading_local.local
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def setUp(test):
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_threading_local.local = _local
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def tearDown(test):
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_threading_local.local = local_orig
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suite.addTest(DocTestSuite('_threading_local',
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setUp=setUp, tearDown=tearDown)
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)
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support.run_unittest(suite)
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if __name__ == '__main__':
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test_main()
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