GNU bug report logs - #24160
[PATCH 1/2] sed: cache results of mbrtowc for speed

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From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
To: 24160 <at> debbugs.gnu.org
Subject: bug#24160: [PATCH 1/2] sed: cache results of mbrtowc for speed
Date: Fri, 05 Aug 2016 22:51:16 +0900

[Message part 1 (text/plain, inline)]

Hi,

We can speeds up sed by caching result of result mbrtowc() for single
byte characters.  It is effective especially in non-UTF8 multibyte
locales which is expensive calculatation.

$ yes $(printf %040d 0) | head -1000000 >k

Before:

$ time -p env LC_ALL=ja_JP.eucjp sed/sed -ne /a.b/p k
real 1.93
user 1.61
sys 0.27

After patching

$ time -p env LC_ALL=ja_JP.eucjp sed/sed -ne /a.b/p k
real 0.46
user 0.42
sys 0.03

Thanks,
Norihiro

[0001-sed-cache-results-of-mbrtowc-for-speed.patch (text/plain, attachment)]

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