GNU bug report logs - #59935
29.0.60; project-list-buffers is slow

Previous Next

Full log

Message #11 received at 59935 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Dmitry Gutov <dgutov <at> yandex.ru>
Cc: 59935 <at> debbugs.gnu.org, juri <at> linkov.net
Subject: Re: bug#59935: 29.0.60; project-list-buffers is slow
Date: Sat, 10 Dec 2022 10:11:15 +0200

> Cc: juri <at> linkov.net
> Date: Sat, 10 Dec 2022 03:49:47 +0200
> From: Dmitry Gutov <dgutov <at> yandex.ru>
> 
> When you invoke 'C-x p C-b', there's a noticeable pause before the
> buffer list is displayed. It's ~400ms over here when there are 46
> non-hidden buffers in the running session.
> 
> What I think is happening, the predicate is called 46, which in turn 
> calls (project-buffers pr) 46 times, and that ends up being 46 times 
> slower than one might have anticipated.
> 
> Not sure what's the best fix here (especially in time for the release),
> but if the FILTER-PREDICATE arg to list-buffers-noselect turned into a
> factory function (e.g. FILTER-PREDICATE-MAKER), that would be one
> solution.
> 
> Another would be to only leave the legacy codepath: it's not affected,
> project-buffers is only called once there.
> 
> Curiously, though, it shows a different list of buffers. It also
> includes "hidden" buffers - diff-syntax, Echo Area, etc. We should look
> into that either way.

I'm not following.  Are you saying that the problem is that the
FILTER-PREDICATE argument to list-buffers-noselect calls
project-buffers for each buffer?  If so, I don't understand why a
trivial change to project-list-buffers could not call project-buffers
just once, and then reuse the value in the call to
list-buffers-noselect both as the BUFFER-LIST argument and (if needed)
in the FILTER-PREDICATE argument, using memq.

If this is not the problem, then what is?

> And the patch is this:

Consequently, I don't understand the rationale for this patch, nor for
the combined one you posted later.  Please elaborate.

P.S. Btw, if you are not sure the multiple calls to project-buffers is
the reason for the slow operation, how about profiling it to be sure?
We may be barking up the wrong tree.

Previous Next

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