[Python-3000-checkins] r64602 - in python/branches/py3k: Lib/test/test_threading_local.py Modules/_threadmodule.c
benjamin.peterson
python-3000-checkins at python.org
Tue Jul 1 01:30:25 CEST 2008
Author: benjamin.peterson
Date: Tue Jul 1 01:30:24 2008
New Revision: 64602
Log:
Merged revisions 64601 via svnmerge from
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.
........
Modified:
python/branches/py3k/ (props changed)
python/branches/py3k/Lib/test/test_threading_local.py
python/branches/py3k/Modules/_threadmodule.c
Modified: python/branches/py3k/Lib/test/test_threading_local.py
==============================================================================
--- python/branches/py3k/Lib/test/test_threading_local.py (original)
+++ python/branches/py3k/Lib/test/test_threading_local.py Tue Jul 1 01:30:24 2008
@@ -42,6 +42,32 @@
deadlist = [weak for weak in weaklist if weak() is None]
self.assert_(len(deadlist) in (n-1, n), (n, len(deadlist)))
+ 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 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 = unittest.TestSuite()
suite.addTest(DocTestSuite('_threading_local'))
Modified: python/branches/py3k/Modules/_threadmodule.c
==============================================================================
--- python/branches/py3k/Modules/_threadmodule.c (original)
+++ python/branches/py3k/Modules/_threadmodule.c Tue Jul 1 01:30:24 2008
@@ -293,7 +293,10 @@
}
}
- else if (self->dict != ldict) {
+
+ /* The call to tp_init above may have caused another thread to run.
+ Install our ldict again. */
+ if (self->dict != ldict) {
Py_CLEAR(self->dict);
Py_INCREF(ldict);
self->dict = ldict;
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