[issue20519] uuid.uuid4().hex generates garbage when ctypes available

[Gustavo J. A. M. Carneiro]

Gustavo J. A. M. Carneiro added the comment:

Well, this isn't a big problem, but I have an application that needs to run with the GC disabled, since it causes pauses of a couple of seconds each time a full collection runs (we have a few million objects allocated).  I will run the GC only once every 3 hours.  So it would be nice if this uuid call didn't generate cycles.

No, I didn't identify the cycle.  All I know is that the garbage below is produced.  If the ctypes module is unavailable, uuid still works but doesn't generate the garbage.

>>> gc.garbage
[(<type '_ctypes.Array'>,), {'raw': <attribute 'raw' of 'c_char_Array_16' objects>, '__module__': 'ctypes', '__dict__': <attribute '__dict__' of 'c_char_Array_16' objects>, '__weakref__': <attribute '__weakref__' of 'c_char_Array_16' objects>, '_length_': 16, '_type_': <class 'ctypes.c_char'>, '__doc__': None, 'value': <attribute 'value' of 'c_char_Array_16' objects>}, <class 'ctypes.c_char_Array_16'>, <attribute '__dict__' of 'c_char_Array_16' objects>, <attribute '__weakref__' of 'c_char_Array_16' objects>, (<class 'ctypes.c_char_Array_16'>, <type '_ctypes.Array'>, <type '_ctypes._CData'>, <type 'object'>), <attribute 'raw' of 'c_char_Array_16' objects>, <attribute 'value' of 'c_char_Array_16' objects>, (<type '_ctypes.Array'>,), {'raw': <attribute 'raw' of 'c_char_Array_16' objects>, '__module__': 'ctypes', '__dict__': <attribute '__dict__' of 'c_char_Array_16' objects>, '__weakref__': <attribute '__weakref__' of 'c_char_Array_16' objects>, '_length_': 16, '_type_': <class 'ctypes.c_char'>, '__doc__': None, 'value': <attribute 'value' of 'c_char_Array_16' objects>}, <class 'ctypes.c_char_Array_16'>, <attribute '__dict__' of 'c_char_Array_16' objects>, <attribute '__weakref__' of 'c_char_Array_16' objects>, (<class 'ctypes.c_char_Array_16'>, <type '_ctypes.Array'>, <type '_ctypes._CData'>, <type 'object'>), <attribute 'raw' of 'c_char_Array_16' objects>, <attribute 'value' of 'c_char_Array_16' objects>, (<type '_ctypes.Array'>,), {'raw': <attribute 'raw' of 'c_char_Array_16' objects>, '__module__': 'ctypes', '__dict__': <attribute '__dict__' of 'c_char_Array_16' objects>, '__weakref__': <attribute '__weakref__' of 'c_char_Array_16' objects>, '_length_': 16, '_type_': <class 'ctypes.c_char'>, '__doc__': None, 'value': <attribute 'value' of 'c_char_Array_16' objects>}, <class 'ctypes.c_char_Array_16'>, <attribute '__dict__' of 'c_char_Array_16' objects>, <attribute '__weakref__' of 'c_char_Array_16' objects>, (<class 'ctypes.c_char_Array_16'>, <type '_ctypes.Array'>, <type '_ctypes._CData'>, <type 'object'>), <attribute 'raw' of 'c_char_Array_16' objects>, <attribute 'value' of 'c_char_Array_16' objects>, (<type '_ctypes.Array'>,), {'raw': <attribute 'raw' of 'c_char_Array_16' objects>, '__module__': 'ctypes', '__dict__': <attribute '__dict__' of 'c_char_Array_16' objects>, '__weakref__': <attribute '__weakref__' of 'c_char_Array_16' objects>, '_length_': 16, '_type_': <class 'ctypes.c_char'>, '__doc__': None, 'value': <attribute 'value' of 'c_char_Array_16' objects>}, <class 'ctypes.c_char_Array_16'>, <attribute '__dict__' of 'c_char_Array_16' objects>, <attribute '__weakref__' of 'c_char_Array_16' objects>, (<class 'ctypes.c_char_Array_16'>, <type '_ctypes.Array'>, <type '_ctypes._CData'>, <type 'object'>), <attribute 'raw' of 'c_char_Array_16' objects>, <attribute 'value' of 'c_char_Array_16' objects>]

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue20519>
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