[Python-Dev] PEP 393 review

[Guido van Rossum]

On Thu, Aug 25, 2011 at 1:24 AM, "Martin v. Löwis" <martin at v.loewis.de> wrote:
>> With this PEP, the unicode object overhead grows to 10 pointer-sized
>> words (including PyObject_HEAD), that's 80 bytes on a 64-bit machine.
>> Does it have any adverse effects?
>
> If I count correctly, it's only three *additional* words (compared to
> 3.2): four new ones, minus one that is removed. In addition, it drops
> a memory block. Assuming a malloc overhead of two pointers per malloc
> block, we get one additional pointer.
[...]

But strings are allocated via PyObject_Malloc(), i.e. the custom
arena-based allocator -- isn't its overhead (for small objects) less
than 2 pointers per block?

-- 
--Guido van Rossum (python.org/~guido)