[Python-Dev] peps: PEP 456: add some of the new implementation details to the PEP's text

Antoine Pitrou solipsis at pitrou.net
Thu Nov 14 10:00:38 CET 2013


On Wed, 13 Nov 2013 23:33:02 +0100 (CET)
christian.heimes <python-checkins at python.org> wrote:
>  
>  
> +Small string optimization
> +=========================
> +
> +Hash functions like SipHash24 have a costly initialization and finalization
> +code that can dominate speed of the algorithm for very short strings. On the
> +other hand Python calculates the hash value of short strings quite often. A
> +simple and fast function for especially for hashing of small strings can make
> +a measurably impact on performance. For example these measurements were taken
> +during a run of Python's regression tests. Additional measurements of other
> +code have shown a similar distribution.

Well, the text above talks about a "measurably (typo?) impact on
performance", but you aren't giving any performance numbers, which
doesn't help the reader of those lines.

Regards

Antoine.




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