diff --git a/Lib/multiprocessing/sharedctypes.py b/Lib/multiprocessing/sharedctypes.py index e83ce584596..1e694da49d9 100644 --- a/Lib/multiprocessing/sharedctypes.py +++ b/Lib/multiprocessing/sharedctypes.py @@ -80,7 +80,9 @@ def RawArray(typecode_or_type, size_or_initializer): type_ = typecode_to_type.get(typecode_or_type, typecode_or_type) if isinstance(size_or_initializer, int): type_ = type_ * size_or_initializer - return _new_value(type_) + obj = _new_value(type_) + ctypes.memset(ctypes.addressof(obj), 0, ctypes.sizeof(obj)) + return obj else: type_ = type_ * len(size_or_initializer) result = _new_value(type_) diff --git a/Lib/test/test_multiprocessing.py b/Lib/test/test_multiprocessing.py index 06449d27837..0ddc71ccd85 100644 --- a/Lib/test/test_multiprocessing.py +++ b/Lib/test/test_multiprocessing.py @@ -928,6 +928,21 @@ def test_array(self, raw=False): self.assertEqual(list(arr[:]), seq) + @unittest.skipIf(c_int is None, "requires _ctypes") + def test_array_from_size(self): + size = 10 + # Test for zeroing (see issue #11675). + # The repetition below strengthens the test by increasing the chances + # of previously allocated non-zero memory being used for the new array + # on the 2nd and 3rd loops. + for _ in range(3): + arr = self.Array('i', size) + self.assertEqual(len(arr), size) + self.assertEqual(list(arr), [0] * size) + arr[:] = range(10) + self.assertEqual(list(arr), list(range(10))) + del arr + @unittest.skipIf(c_int is None, "requires _ctypes") def test_rawarray(self): self.test_array(raw=True) diff --git a/Misc/NEWS b/Misc/NEWS index 947777a29ee..17b5d7e3238 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -10,6 +10,10 @@ What's New in Python 3.3 Alpha 1? Core and Builtins ----------------- +- Issue #11675: multiprocessing.[Raw]Array objects created from an integer size + are now zeroed on creation. This matches the behaviour specified by the + documentation. + - Issue #10998: Remove mentions of -Q, sys.flags.division_warning and Py_DivisionWarningFlag left over from Python 2.