From: "Clément Pit--Claudel" <clement.pit@gmail.com>
To: Emacs developers <emacs-devel@gnu.org>
Subject: What makes set-window-buffer slow?
Date: Thu, 23 Jun 2016 11:48:52 -0400 [thread overview]
Message-ID: <576C04E4.9040000@gmail.com> (raw)
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Hi emacs-devel,
This is a rather ill-defined question. I've just been through a round of 20 emails with a user, trying to understand which part of one of my packages made Proof General horribly slow. We progressively narrowed it down to this:
(set-window-buffer win buf)
... which is definitely not what I expected. Note that:
* This happens in emacs -Q with just Proof General loaded
* The two hooks that set-window-buffer calls are nil (window-hscroll-functions and window-configuration-change-hook)
* This is called about 200 times (once for each full message received from a subprocess).
* Commenting out this line makes processing of these ~200 messages from the subprocess take 5 seconds instead of 50.
The (most) surprising part here is that the following change makes it fast again:
(unless (eq (window-buffer win) buf)
(set-window-buffer win buf))
IOW, in most cases, the window in question already displays buf; yet, the calls are extremely slow.
Is anyone familiar with such an issue? This is in GNU Emacs 24.4.1; I can't reproduce it myself, but I can ask for more information if needed.
Cheers,
Clément.
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next reply other threads:[~2016-06-23 15:48 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-23 15:48 Clément Pit--Claudel [this message]
2016-06-23 16:01 ` What makes set-window-buffer slow? Andreas Schwab
2016-06-23 17:45 ` Clément Pit--Claudel
2016-06-23 18:12 ` Alan Mackenzie
2016-06-23 18:30 ` Clément Pit--Claudel
2016-06-23 19:11 ` Eli Zaretskii
2016-06-23 21:23 ` Clément Pit--Claudel
2016-06-24 6:54 ` Eli Zaretskii
2016-06-24 12:33 ` Clément Pit--Claudel
2016-06-24 13:56 ` Eli Zaretskii
2016-06-24 14:19 ` Clément Pit--Claudel
2016-06-24 18:31 ` Clément Pit--Claudel
2016-06-24 19:13 ` Eli Zaretskii
2016-06-24 21:33 ` Clément Pit--Claudel
2016-06-25 7:30 ` Eli Zaretskii
2016-06-25 14:07 ` Clément Pit--Claudel
2016-06-25 14:27 ` Eli Zaretskii
2016-06-25 14:39 ` Eli Zaretskii
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