Message 178837 - Python tracker

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Author	Giovanni.Bajo
Recipients	Arfrever, Bob.Ziuchkovski, Giovanni.Bajo, PaulMcMillan, ReneSac, Vlado.Boza, alex, arigo, benjamin.peterson, camara, christian.heimes, cvrebert, dmalcolm, gregory.p.smith, iElectric, koniiiik, lemburg, mark.dickinson, ncoghlan, sbermeister, serhiy.storchaka, vstinner, Łukasz.Rekucki
Date	2013年01月02日.18:56:26
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<E0D0C138-C2B0-40E1-8819-42B8B88272B8@gmail.com>
In-reply-to	<1357152712.45.0.811391231368.issue14621@psf.upfronthosting.co.za>

Content
Il giorno 02/gen/2013, alle ore 19:51, Christian Heimes <report@bugs.python.org> ha scritto: > > Christian Heimes added the comment: > > Giovanni, why do you think that hashing of unicode strings is slower than byte strings? > > First of all ASCII only unicode strings are packed and use just one byte per char. CPython's FNV implementation processes one element in each cycle, that is one byte for bytes and ASCII unicode, two bytes for UCS-2 and four bytes for UCS-4. Bytes and UCS-4 strings require the same amount of CPU instructions. Ah sorry, I stand corrected (though packing wasn't there in 3.0, was it? I was specifically referred to the 2.x -> 3.0 transition). -- Giovanni Bajo My Blog: http://giovanni.bajo.it

Content

Il giorno 02/gen/2013, alle ore 19:51, Christian Heimes <report@bugs.python.org> ha scritto:
> 
> Christian Heimes added the comment:
> 
> Giovanni, why do you think that hashing of unicode strings is slower than byte strings? 
> 
> First of all ASCII only unicode strings are packed and use just one byte per char. CPython's FNV implementation processes one element in each cycle, that is one byte for bytes and ASCII unicode, two bytes for UCS-2 and four bytes for UCS-4. Bytes and UCS-4 strings require the same amount of CPU instructions.
Ah sorry, I stand corrected (though packing wasn't there in 3.0, was it? I was specifically referred to the 2.x -> 3.0 transition).
-- 
Giovanni Bajo
My Blog: http://giovanni.bajo.it

History
Date	User	Action	Args
2013年01月02日 18:56:26	Giovanni.Bajo	set	recipients: + Giovanni.Bajo, lemburg, arigo, gregory.p.smith, mark.dickinson, ncoghlan, vstinner, christian.heimes, benjamin.peterson, iElectric, Arfrever, alex, cvrebert, dmalcolm, PaulMcMillan, serhiy.storchaka, Vlado.Boza, koniiiik, sbermeister, camara, Łukasz.Rekucki, ReneSac, Bob.Ziuchkovski
2013年01月02日 18:56:26	Giovanni.Bajo	link	issue14621 messages
2013年01月02日 18:56:26	Giovanni.Bajo	create

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