GNU bug report logs - #17025
[PATCH] grep: matching line-by-line with regex

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Norihiro Tanaka <noritnk <at> kcn.ne.jp>
To: submit <at> debbugs.gnu.org
Subject: [PATCH] grep: matching line-by-line with regex
Date: Mon, 17 Mar 2014 23:49:20 +0900

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

Package: grep
Tags: patch

I ran following test, which used the regex enging in non-UTF8 locale.

$ yes abcd.abc | head -10000 > m
$ time -p env LC_ALL=ja_JP.eucJP src/grep abcd.abd m
real 7.28
user 6.36
sys 0.57

It's extremally slow.  When regex engine is used in grep, a text is
splitted by line.  However all of buffer is passed to re_search and
re_match.  I seem that it's wrong.

Norihiro

[patch1.txt (text/plain, attachment)]

Message #8 received at 17025 <at> debbugs.gnu.org (full text, mbox):

From: Paolo Bonzini <bonzini <at> gnu.org>
To: Norihiro Tanaka <noritnk <at> kcn.ne.jp>, 17025 <at> debbugs.gnu.org
Subject: Re: bug#17025: [PATCH] grep: matching line-by-line with regex
Date: Tue, 01 Apr 2014 11:10:38 +0200

Il 17/03/2014 15:49, Norihiro Tanaka ha scritto:
> Package: grep
> Tags: patch
>
> I ran following test, which used the regex enging in non-UTF8 locale.
>
> $ yes abcd.abc | head -10000 > m
> $ time -p env LC_ALL=ja_JP.eucJP src/grep abcd.abd m
> real 7.28
> user 6.36
> sys 0.57
>
> It's extremally slow.  When regex engine is used in grep, a text is
> splitted by line.  However all of buffer is passed to re_search and
> re_match.  I seem that it's wrong.

Yes, very good catch.

It's likely that the old bytecode matcher didn't care, but the new one 
in glibc has to process even the "ignored" part of the buffer to find 
the boundaries of multibyte characters.

Paolo

Message #13 received at 17025-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Norihiro Tanaka <noritnk <at> kcn.ne.jp>, 17025-done <at> debbugs.gnu.org
Cc: Paolo Bonzini <bonzini <at> gnu.org>, 17156 <at> debbugs.gnu.org
Subject: Re: bug#17025: [PATCH] grep: matching line-by-line with regex
Date: Sat, 05 Apr 2014 22:26:56 -0700

Thanks for this bug report and patch.  Paolo wrote it up in 
<http://bugs.gnu.org/17156#14>, and I installed it into the savannah 
grep master and am marking Bug#17025 as done.

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