[Python-Dev] Python hash function (original) (raw)

damien morton dmorton@bitfurnace.com
Wed, 25 Jun 2003 01:24:23 -0400

I do know about ob_shash, and youre probably right that most strings used by pystone are interned. Even so, my running python/pystone through vtune showed that as much time is spent in string_hash() as lookdict_string(). Lookdict_string() is, of course, called many more times than string_hash() - but the total self time for each function is comparable.

Not only does the current hash function use a multiply for every character, but it doesn't parralelise very well. The functions I have been playing with are about 4 times faster than the current function, while using only half the multiplies, adds and loop iterations.

-----Original Message----- From: Neil Schemenauer [mailto:nas-python@python.ca] Sent: Wednesday, 25 June 2003 00:27 To: damien.morton@acm.org Cc: python-dev@python.org Subject: Re: [Python-Dev] Python hash function

Damien Morton wrote: > Maddeningly, I havent been able to translate these near-perfect > distributions into improvements in pystones. No time to look at this in deal but do you know about obshash? I suspect most strings used by pystone are interned. Neil