Armin Rigo wrote: > Hi, > > Ok, here is the reason for the leak... > > There is in scipy a type called 'int32_arrtype' which inherits from both > another scipy type called 'signedinteger_arrtype', and from 'int'. > Obscure! This is not 100% officially allowed: you are inheriting from > two C types. You're living dangerously! > > Now in this case it mostly works as expected, because the parent scipy > type has no field at all, so it's mostly like inheriting from both > 'object' and 'int' -- which is allowed, or would be if the bases were > written in the opposite order. But still, something confuses the > fragile logic of typeobject.c. (I'll leave this bit to scipy people to > debug :-) > > The net result is that unless you force your own tp_free as in revision > 1490, the type 'int32_arrtype' has tp_free set to int_free(), which is > the normal tp_free of 'int' objects. This causes all deallocated > int32_arrtype instances to be added to the CPython free list of integers > instead of being freed!
I can confirm that indeed the int32_arrtype object gets the tp_free slot from it's second parent (the python integer type) instead of its first parent (the new, empty signed integer type). I just did a printf after PyType_Ready was called to see what the tp_free slot contained, and indeed it contained the wrong thing. I suspect this may also be true of the float64_arrtype as well (which inherits from Python's float type). What I don't understand is why the tp_free slot from the second base type got copied over into the tp_free slot of the child. It should have received the tp_free slot of the first parent, right? I'm still looking for why that would be the case. I think, though, Armin has identified the real culprit of the problem. I apologize for any consternation over the memory manager that may have taken place. This problem is obviously an issue of dual inheritance in C. I understand this is not well tested code, but in principle it should work correctly, right? I'll keep looking to see if I made a mistake in believing that the int32_arrtype should have inherited its tp_free slot from the first parent and not the second. -Travis _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com