Issue #15781: Fix two small race conditions in import's module locking.

This commit is contained in:
Antoine Pitrou 2012-08-28 00:24:52 +02:00
parent 79dbded0fa
commit 4f0338cab7
5 changed files with 3679 additions and 3655 deletions

View File

@ -268,8 +268,10 @@ def _get_module_lock(name):
Should only be called with the import lock taken."""
lock = None
if name in _module_locks:
try:
lock = _module_locks[name]()
except KeyError:
pass
if lock is None:
if _thread is None:
lock = _DummyModuleLock(name)
@ -543,6 +545,9 @@ def module_for_loader(fxn):
# implicitly imports 'locale' and would otherwise trigger an
# infinite loop.
module = new_module(fullname)
# This must be done before putting the module in sys.modules
# (otherwise an optimization shortcut in import.c becomes wrong)
module.__initializing__ = True
sys.modules[fullname] = module
module.__loader__ = self
try:
@ -554,8 +559,9 @@ def module_for_loader(fxn):
module.__package__ = fullname
else:
module.__package__ = fullname.rpartition('.')[0]
try:
else:
module.__initializing__ = True
try:
# If __package__ was not set above, __import__() will do it later.
return fxn(self, module, *args, **kwargs)
except:

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@ -224,7 +224,17 @@ class ThreadedImportTests(unittest.TestCase):
@reap_threads
def test_main():
run_unittest(ThreadedImportTests)
old_switchinterval = None
try:
old_switchinterval = sys.getswitchinterval()
sys.setswitchinterval(0.00000001)
except AttributeError:
pass
try:
run_unittest(ThreadedImportTests)
finally:
if old_switchinterval is not None:
sys.setswitchinterval(old_switchinterval)
if __name__ == "__main__":
test_main()

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@ -10,6 +10,8 @@ What's New in Python 3.3.0 Release Candidate 2?
Core and Builtins
-----------------
- Issue #15781: Fix two small race conditions in import's module locking.
Library
-------

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@ -1408,7 +1408,11 @@ PyImport_ImportModuleLevelObject(PyObject *name, PyObject *given_globals,
int initializing = 0;
Py_INCREF(mod);
/* Only call _bootstrap._lock_unlock_module() if __initializing__ is true. */
/* Optimization: only call _bootstrap._lock_unlock_module() if
__initializing__ is true.
NOTE: because of this, __initializing__ must be set *before*
stuffing the new module in sys.modules.
*/
value = _PyObject_GetAttrId(mod, &PyId___initializing__);
if (value == NULL)
PyErr_Clear();

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