[Python-3000] Where is PyUnicodeObject->hash supposed to be set? (original) (raw)

Nicholas Bastin nick.bastin at gmail.com
Fri Sep 7 23:13:31 CEST 2007

On 9/7/07, Guido van Rossum <guido at python.org> wrote:

It should be set in unicodehash(). If you compare the trunk version of that function with the py3k branch version, you see that it's been refactored, and in the refactoring, setting ->hash was omitted. It should be trivial to put it back.

Putting it back nets an average 1.8% performance gain for pystone, but probably there were other cases that were extremely bad given this behaviour. We're still left with another 5 million 'extra' calls to PyDict_GetItem in 3.0 over 2.6 in a 100000 cycle pystone run, so I'll look around into those, but I suspect none of them will generate any larger performance gain.

Someone with more experience than I in the 3.0 development cycle will be able to determine what macro-level optimizations / refactoring make sense, and what design decisions we're just going to have to pay for. At the moment (and probably for the forseeable moments), I'm focusing on small improvements across the codebase.

-- Nick

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