Message 161301 - Python tracker

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In-reply-to
Author	serhiy.storchaka
Recipients	ezio.melotti, lemburg, pitrou, serhiy.storchaka, vstinner
Date	2012年05月21日.22:19:25
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1337638770.26.0.783937266614.issue14874@psf.upfronthosting.co.za>

Content
Charmap decoders are not as important as UTF decoders, but are still widely used. In Python 3.3 with PEP 393 they slowed down 4x. The proposed patch restores the performance. Optimized only the most common case, when the decoder is specified by the UCS2 table with length >= 256. Map-based decoders translated to table-based. UCS1 tables widened to UCS2 by adding 257th fake characters. Benchmark results: 3.2 3.3(vanilla) 3.3(patched) cp1251 'A'10000 111 (+10%) 31 (+294%) 122 cp1251 '\xa0'10000 111 (+8%) 29 (+314%) 120 cp1251 '\u0402'*10000 111 (+6%) 25 (+372%) 118

Content

Charmap decoders are not as important as UTF decoders, but are still widely used. In Python 3.3 with PEP 393 they slowed down 4x. The proposed patch restores the performance.
Optimized only the most common case, when the decoder is specified by the UCS2 table with length >= 256. Map-based decoders translated to table-based. UCS1 tables widened to UCS2 by adding 257th fake characters.
Benchmark results:
 3.2 3.3(vanilla) 3.3(patched)
cp1251 'A'*10000 111 (+10%) 31 (+294%) 122
cp1251 '\xa0'*10000 111 (+8%) 29 (+314%) 120
cp1251 '\u0402'*10000 111 (+6%) 25 (+372%) 118

History
Date	User	Action	Args
2012年05月21日 22:19:32	serhiy.storchaka	set	recipients: + serhiy.storchaka, lemburg, pitrou, vstinner, ezio.melotti
2012年05月21日 22:19:30	serhiy.storchaka	set	messageid: <1337638770.26.0.783937266614.issue14874@psf.upfronthosting.co.za>
2012年05月21日 22:19:29	serhiy.storchaka	link	issue14874 messages
2012年05月21日 22:19:29	serhiy.storchaka	create

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