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What makes set-window-buffer slow?
From: |
Clément Pit--Claudel |
Subject: |
What makes set-window-buffer slow? |
Date: |
Thu, 23 Jun 2016 11:48:52 -0400 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 |
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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- What makes set-window-buffer slow?,
Clément Pit--Claudel <=
- Re: What makes set-window-buffer slow?, Andreas Schwab, 2016/06/23
- Re: What makes set-window-buffer slow?, Clément Pit--Claudel, 2016/06/23
- Re: What makes set-window-buffer slow?, Alan Mackenzie, 2016/06/23
- Re: What makes set-window-buffer slow?, Clément Pit--Claudel, 2016/06/23
- Re: What makes set-window-buffer slow?, Eli Zaretskii, 2016/06/23
- Re: What makes set-window-buffer slow?, Clément Pit--Claudel, 2016/06/23
- Re: What makes set-window-buffer slow?, Eli Zaretskii, 2016/06/24
- Re: What makes set-window-buffer slow?, Clément Pit--Claudel, 2016/06/24
- Re: What makes set-window-buffer slow?, Eli Zaretskii, 2016/06/24
- Re: What makes set-window-buffer slow?, Clément Pit--Claudel, 2016/06/24