GNU bug report logs - #59787
29.0.60; Very slow pos-visible-in-window-p with long truncated lines

Previous Next

Full log

View this message in rfc822 format

From: Juri Linkov <juri <at> linkov.net>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 59787 <at> debbugs.gnu.org
Subject: bug#59787: 29.0.60; Very slow pos-visible-in-window-p with long truncated lines
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?

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.