Message 186403 - Python tracker

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In-reply-to
Author	pitrou
Recipients	asvetlov, christian.heimes, gregory.p.smith, jcea, mark.dickinson, pitrou, python-dev, rhettinger, serhiy.storchaka, skrah, tim.peters, vstinner
Date	2013年04月09日.13:34:33
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1365514473.29.0.657560354102.issue16427@psf.upfronthosting.co.za>

Content
Well, the quality of the hash function is clearly reduced: >>> hash("abcdefgh") & 0xff 206 >>> hash("abcdefgi") & 0xff 206 >>> hash("abcdefgj") & 0xff 206 >>> hash("abxxxxxx") & 0xff 206 >>> hash("aaaaaa11") & 0xff 206 >>> hash("aaaaaa12") & 0xff 206 Now to know if that may produce slowdowns in some situations... (dicts and sets have a sophisticated probing algorithm which takes into account the whole hash value, not the masked one).

Content

Well, the quality of the hash function is clearly reduced:
>>> hash("abcdefgh") & 0xff
206
>>> hash("abcdefgi") & 0xff
206
>>> hash("abcdefgj") & 0xff
206
>>> hash("abxxxxxx") & 0xff
206
>>> hash("aaaaaa11") & 0xff
206
>>> hash("aaaaaa12") & 0xff
206
Now to know if that may produce slowdowns in some situations... (dicts and sets have a sophisticated probing algorithm which takes into account the whole hash value, not the masked one).

History
Date	User	Action	Args
2013年04月09日 13:34:33	pitrou	set	recipients: + pitrou, tim.peters, rhettinger, gregory.p.smith, jcea, mark.dickinson, vstinner, christian.heimes, asvetlov, skrah, python-dev, serhiy.storchaka
2013年04月09日 13:34:33	pitrou	set	messageid: <1365514473.29.0.657560354102.issue16427@psf.upfronthosting.co.za>
2013年04月09日 13:34:33	pitrou	link	issue16427 messages
2013年04月09日 13:34:33	pitrou	create

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