Message 55547 - Python tracker

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In-reply-to
Author	ggenellina
Recipients	ggenellina, inducer
Date	2007年09月01日.02:01:48
SpamBayes Score	0.27822265
Marked as misclassified	No
Message-id	<1188612109.5.0.491793802821.issue1045@psf.upfronthosting.co.za>

Content
I've narrowed the problem to the usage of generator expressions. Generator expressions appear to be MUCH slower on 2.5 than on 2.4. >python -m timeit "tuple([1 for _ in xrange(3)])" 2.4 -> 2.23us 2.5 -> 2.31us (a bit slower, but not so much) >python -m timeit "tuple(1 for _ in xrange(3))" 2.4 -> 3.32us 2.5 -> 8.03us (240% slower than 2.4) It appears to be a fixed cost, or startup cost, of the generator expression; differences get smaller when building large tuples (but always Python 2.5 runs slower than 2.4)

Content

I've narrowed the problem to the usage of generator expressions. 
Generator expressions appear to be MUCH slower on 2.5 than on 2.4.
>python -m timeit "tuple([1 for _ in xrange(3)])"
2.4 -> 2.23us
2.5 -> 2.31us (a bit slower, but not so much)
>python -m timeit "tuple(1 for _ in xrange(3))"
2.4 -> 3.32us
2.5 -> 8.03us (240% slower than 2.4)
It appears to be a fixed cost, or startup cost, of the generator 
expression; differences get smaller when building large tuples (but 
always Python 2.5 runs slower than 2.4)

History
Date	User	Action	Args
2007年09月01日 02:01:50	ggenellina	set	spambayes_score: 0.278223 -> 0.27822265 recipients: + ggenellina, inducer
2007年09月01日 02:01:49	ggenellina	set	spambayes_score: 0.278223 -> 0.278223 messageid: <1188612109.5.0.491793802821.issue1045@psf.upfronthosting.co.za>
2007年09月01日 02:01:49	ggenellina	link	issue1045 messages
2007年09月01日 02:01:48	ggenellina	create

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