[Python-Dev] dictnotes.txt out of date?

[Mark Shannon]

Eli Bendersky wrote:
> Hi pydev,
> 
> I was looking at the memory allocation strategy of dict, out of
> curiosity, and noted that Objects/dictnotes.txt is out of date as far
> as the parameters go. It says about PyDict_STARTSIZE:
> 
> ----
> * PyDict_STARTSIZE. Starting size of dict (unless an instance dict).
>     Currently set to 8. Must be a power of two.
>     New dicts have to zero-out every cell.
>     Increasing improves the sparseness of small dictionaries but costs
>     time to read in the additional cache lines if they are not already
>     in cache. That case is common when keyword arguments are passed.
>     Prior to version 3.3, PyDict_MINSIZE was used as the starting size
>     of a new dict.
> -----
> 
> Although it mentions 3.3, I find no reference to PyDict_STARTSIZE in
> the code anywhere.
> Also it mentions PyDict_MINSIZE, which doesn't exist any more - having
> been replaced by Py_DICT_MINZISE_SPLIT and Py_DICT_COMBINED.

That's my fault. I didn't update dictnotes.txt when I changed 
PyDict_STARTSIZE to PyDict_MINSIZE_COMBINED.

> 
> I don't know what else is out of date, just looked at those and they
> were. Maybe it would make sense to kill dictnotes.txt, folding some of
> its more important contents in to comments in dictobject.c, since the
> latter has a higher chance of being maintained along with code
> changes?

I think that the parts of dictnotes.txt that just duplicate comments in
dictobject.c should be removed.
However, I think it is worth keeping dictnotes.txt as it has historical
information and results of previous experiments.

Cheers,
Mark