* bug#59787: 29.0.60; Very slow pos-visible-in-window-p with long truncated lines
@ 2022-12-02 20:09 Eli Zaretskii
2022-12-07 7:58 ` Juri Linkov
0 siblings, 1 reply; 3+ messages in thread
From: Eli Zaretskii @ 2022-12-02 20:09 UTC (permalink / raw)
To: 59787
As reported in https://debbugs.gnu.org/cgi/bugreport.cgi?bug=56682#1977:
2. after starting Isearch at a large column number,
Emacs hangs up indefinitely, e.g. with
'M-g TAB 10000000 RET C-s' then even C-g doesn't get out.
Debugging shows that the problem is in 'isearch-update'
where the call to 'pos-visible-in-window-group-p' doesn't return.
When this call is removed, the search is instantaneous.
(Optimizing lazy-highlight is a separate problem in bug#56815.)
The problem is that pos-visible-in-window-p starts from window-start point
and goes to the POSITION passed as argument using move_it_to, which in this
case is very slow, because it has all the 10000000 columns to traverse.
The solution is to introduce shortcuts into pos_visible_p in this case.
In GNU Emacs 29.0.60 (build 17, i686-pc-mingw32) of 2022-12-02 built on
HOME-C4E4A596F7
Repository revision: 4b3eb928fed4b236d1ae06ae7d9d51a4466554d2
Repository branch: emacs-29
Windowing system distributor 'Microsoft Corp.', version 5.1.2600
System Description: Microsoft Windows XP Service Pack 3 (v5.1.0.2600)
Configured using:
'configure -C --prefix=/d/usr --with-wide-int
--enable-checking=yes,glyphs 'CFLAGS=-O0 -gdwarf-4 -g3''
Configured features:
ACL GIF GMP GNUTLS HARFBUZZ JPEG JSON LCMS2 LIBXML2 MODULES NOTIFY
W32NOTIFY PDUMPER PNG RSVG SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS TREE_SITTER WEBP XPM ZLIB
Important settings:
value of $LANG: ENU
locale-coding-system: cp1255
Major mode: Lisp Interaction
Minor modes in effect:
tooltip-mode: t
global-eldoc-mode: t
eldoc-mode: t
show-paren-mode: t
electric-indent-mode: t
mouse-wheel-mode: t
tool-bar-mode: t
menu-bar-mode: t
file-name-shadow-mode: t
global-font-lock-mode: t
font-lock-mode: t
blink-cursor-mode: t
line-number-mode: t
indent-tabs-mode: t
transient-mark-mode: t
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t
Load-path shadows:
None found.
Features:
(shadow sort mail-extr dabbrev emacsbug message mailcap yank-media puny
dired dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg
rfc6068 epg-config gnus-util text-property-search time-date subr-x
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader cl-loaddefs cl-lib sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils rmc iso-transl tooltip cconv eldoc paren
electric uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel
dos-w32 ls-lisp disp-table term/w32-win w32-win w32-vars term/common-win
tool-bar dnd fontset image regexp-opt fringe tabulated-list replace
newcomment text-mode lisp-mode prog-mode register page tab-bar menu-bar
rfn-eshadow isearch easymenu timer select scroll-bar mouse jit-lock
font-lock syntax font-core term/tty-colors frame minibuffer nadvice seq
simple cl-generic indonesian philippine cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms
cp51932 hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese composite emoji-zwj charscript charprop case-table
epa-hook jka-cmpr-hook help abbrev obarray oclosure cl-preloaded button
loaddefs theme-loaddefs faces cus-face macroexp files window
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget keymap hashtable-print-readable backquote threads
w32notify w32 lcms2 multi-tty make-network-process emacs)
Memory information:
((conses 16 43232 13224)
(symbols 48 6330 6)
(strings 16 16709 3199)
(string-bytes 1 406733)
(vectors 16 9402)
(vector-slots 8 147021 11501)
(floats 8 25 28)
(intervals 40 273 112)
(buffers 896 10))
^ permalink raw reply [flat|nested] 3+ messages in thread
* bug#59787: 29.0.60; Very slow pos-visible-in-window-p with long truncated lines
2022-12-02 20:09 bug#59787: 29.0.60; Very slow pos-visible-in-window-p with long truncated lines Eli Zaretskii
@ 2022-12-07 7:58 ` Juri Linkov
2022-12-07 14:25 ` Eli Zaretskii
0 siblings, 1 reply; 3+ messages in thread
From: Juri Linkov @ 2022-12-07 7:58 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: 59787
> As reported in https://debbugs.gnu.org/cgi/bugreport.cgi?bug=56682#1977:
>
> 2. after starting Isearch at a large column number,
> Emacs hangs up indefinitely, e.g. with
> 'M-g TAB 10000000 RET C-s' then even C-g doesn't get out.
> Debugging shows that the problem is in 'isearch-update'
> where the call to 'pos-visible-in-window-group-p' doesn't return.
> When this call is removed, the search is instantaneous.
> (Optimizing lazy-highlight is a separate problem in bug#56815.)
>
> The problem is that pos-visible-in-window-p starts from window-start point
> and goes to the POSITION passed as argument using move_it_to, which in this
> case is very slow, because it has all the 10000000 columns to traverse.
>
> The solution is to introduce shortcuts into pos_visible_p in this case.
Could you explain why pos-visible-in-window-p is instantaneous at any
position when long lines are not truncated. Why it doesn't need to
traverse 10000000 columns in this case?
^ permalink raw reply [flat|nested] 3+ messages in thread
* bug#59787: 29.0.60; Very slow pos-visible-in-window-p with long truncated lines
2022-12-07 7:58 ` Juri Linkov
@ 2022-12-07 14:25 ` Eli Zaretskii
0 siblings, 0 replies; 3+ messages in thread
From: Eli Zaretskii @ 2022-12-07 14:25 UTC (permalink / raw)
To: Juri Linkov; +Cc: 59787
> From: Juri Linkov <juri@linkov.net>
> Cc: 59787@debbugs.gnu.org
> Date: Wed, 07 Dec 2022 09:58:40 +0200
>
> > As reported in https://debbugs.gnu.org/cgi/bugreport.cgi?bug=56682#1977:
> >
> > 2. after starting Isearch at a large column number,
> > Emacs hangs up indefinitely, e.g. with
> > 'M-g TAB 10000000 RET C-s' then even C-g doesn't get out.
> > Debugging shows that the problem is in 'isearch-update'
> > where the call to 'pos-visible-in-window-group-p' doesn't return.
> > When this call is removed, the search is instantaneous.
> > (Optimizing lazy-highlight is a separate problem in bug#56815.)
> >
> > The problem is that pos-visible-in-window-p starts from window-start point
> > and goes to the POSITION passed as argument using move_it_to, which in this
> > case is very slow, because it has all the 10000000 columns to traverse.
> >
> > The solution is to introduce shortcuts into pos_visible_p in this case.
>
> Could you explain why pos-visible-in-window-p is instantaneous at any
> position when long lines are not truncated. Why it doesn't need to
> traverse 10000000 columns in this case?
Because when lines are wrapped, window-start is at the first visible
character in the window, which is much closer to point than 10000000
characters, even with today's huge screens. And
pos-visible-in-window-p starts from window-start position, because
that's where it _knows_ the exact X coordinate. (It needs the X
coordinate to start from so that it could report the X coordinate of
point when the 3rd argument is non-nil.)
By contrast, when lines are truncated and the window is hscrolled,
window-start is at the first character of the first line, which in the
above case is 10000000 characters before the first visible character.
So starting from window-start will need to traverse 10000000 invisible
characters before it gets to point. (Which if you think about it,
almost suggests the shortcut for when the lines are very long...)
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-12-02 20:09 bug#59787: 29.0.60; Very slow pos-visible-in-window-p with long truncated lines Eli Zaretskii
2022-12-07 7:58 ` Juri Linkov
2022-12-07 14:25 ` Eli Zaretskii
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