GNU bug report logs - #18778
noticeable slowdown for buffers with long lines, word-wrap, and brackets

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Ivan Shmakov <ivan <at> siamics.net>
Subject: bug#18778: closed (Re: bug#18778: noticeable slowdown for buffers
 with long lines, word-wrap, and brackets )
Date: Wed, 29 Oct 2014 19:33:02 +0000

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Your bug report

#18778: noticeable slowdown for buffers with long lines, word-wrap, and brackets 

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 18778 <at> debbugs.gnu.org.

-- 
18778: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=18778
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Ivan Shmakov <ivan <at> siamics.net>
To: 18778-done <at> debbugs.gnu.org
Subject: Re: bug#18778: noticeable slowdown for buffers with long lines,
 word-wrap, and brackets 
Date: Wed, 29 Oct 2014 19:31:59 +0000

>>>>> Eli Zaretskii <eliz <at> gnu.org> writes:

 > In trunk revision 118179 I introduced an optimization that fixes
 > these situations.

	As of 4fd1634dbdd8, I no longer observe this issue, thus closing
	this bug.

	Thanks again.

-- 
FSF associate member #7257  http://boycottsystemd.org/  … 3013 B6A0 230E 334A

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From: Ivan Shmakov <ivan <at> siamics.net>
To: submit <at> debbugs.gnu.org
Subject: noticeable slowdown for buffers with long lines, word-wrap,
 and brackets 
Date: Mon, 20 Oct 2014 19:17:28 +0000

Package: emacs
X-Debbugs-Cc: Eli Zaretskii <eliz <at> gnu.org>

>>>>> Eli Zaretskii <eliz <at> gnu.org> writes:

[…]

 > In addition, one of the new UBA features, the so-called Bidirectional
 > Parentheses Algorithm (BPA), affects pure-ASCII text as well, and
 > specifically editing of program sources (which widely use parentheses
 > and brackets of several kinds).

 > The result is some small slowdown -- a few percents in my testing --
 > in redisplay operations.  If more significant slowdown will be
 > reported in some special cases, I will try to find optimizations to
 > countermand that.

	It seems that I’ve just found such a case for 13a3ad6b39c0.

	To reproduce:

	• create a buffer with long lines (see below for the example
	  I’ve used), and (setq word-wrap t line-move-visual nil) there;

	• now, enclose every line in [, ] brackets (as in: M-x
	  replace-regexp RET .* RET [\&] RET; parentheses or curly
	  braces also exhibit the issue.)

	For the resulting buffer, operations like (next-line) or even
	(recenter) now result in a noticeable delay.

	The issue doesn’t appear when word-wrap is not used, or when
	there’s no brackets in the buffer.  Neither the issue appears in
	Emacs built 2014-10-09 from a then-recent Git clone.

	I’ve used the output of the following Shell command as a test.

$ head -n 8192 < /usr/share/dict/american-english | fmt -w 1024 

[…]

-- 
FSF associate member #7257  http://boycottsystemd.org/  … 3013 B6A0 230E 334A

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