[Python-Dev] Activating pymalloc

[Tim Peters]

[M.-A. Lemburg, on PyMem_xxx still using malloc/free even when pymalloc
 is enabled]

> Depends on how you define PyMem_* ...

I could have guessed that <wink>.

> If you are saying that these macros/functions are only intended to
> allocate memory blocks which Python will use, then it's probably OK to
> let pymalloc handle these as well.
>
> If, for some reason, you intend to share the memory
> with some other process/DLL/whatever, then I'm not
> sure if this continues to work with pymalloc -- could
> be that the platform's malloc() uses flags/locks etc.
> to manage sharing. Just a thought, probably just FUD.
>
> ALAS, the only way to find out, is to try it.

It's not entirely FUD.  At least on Windows, you can get into a state where
using memory APIs "from the same family" can nevertheless end up using
different heaps, and then passing addresses around is a nightmare when one
DLL tries to free memory obtained in a different DLL.  As a uniform way to
spell "use the Python DLL's view of what 'the heap' is to allocate and
free", PyMem_XXX serve a real purpose there.  But extensions currently mix,
e.g., PyMem_Malloc() with free() too.