bug#70049: 30.0.50; (server-running-p) in mode line freezes emacs

[Pedro Andres Aranda Gutierrez <paaguti@gmail.com>]

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Hey,

When I say freeze, I mean it becomes irresponsive and does not respond to
Ctrl-G and GNOME detects the situation, opening a 'force quit' dialog. It
also happens in macOS, and there I can only force quit emacs. I've opened
this bug, because there was something similar around putting a VC indicator
in the mode-line.

It might not be solvable, but at least I think it is worth discussing and
documenting. Who knows if this could not end in a DONT-DO sort of document,
which might also be of some merit and use.

Happy easter, /PA


On Thu, 28 Mar 2024 at 12:46, Eli Zaretskii <eliz@gnu.org> wrote:

> > Date: Thu, 28 Mar 2024 11:45:16 +0100
> > From: "Pedro A. Aranda" <paaguti@gmail.com>
> >
> > Place the following file as init.el in a directory (e.g. ~/.demacs.d)
> >
> >
> > ---- cut here ----
> > ;; Mode line settings
> >
> > (defun server-running-indicator()
> >    (when (server-running-p) "S "))
> > ;;  (unless (null server-process) "S "))
> >
> > ;; (setq-default mode-line-right-align-edge 'right-fringe)
> > (setq-default mode-line-format
> >                (list
> >                       '(:eval (propertize (server-running-indicator)
> >                                           'face 'mode-line-buffer-id))
> >
> >                       mode-line-modified
> >                       " "
> >                       mode-line-buffer-identification
> >                       " "
> >                       mode-line-position))
> > ---- cut here ----
> >
> > run emacs as
> > /usr/bin/emacs --init-directory ~/.demacs.d
> >
> > On the emacs window, click on the lower left corner and resize it with
> > the mouse. No hangs are observed.
> >
> > Now, active server-mode with
> > M-x server-mode
> >
> > Try again to resize the emacs window with the mouse. Emacs freezes.
>
> I seem to be unable to reproduce this.
>
> Does the freeze happen only if you resize the frame?  What if you just
> drag the mode line to resize the window?
>
> And when you say "freezes", does it mean Emacs uses 100% of a CPU's
> execution unit, or does it mean it waits for something doing nothing?
>
> Btw, in general, having arbitrary expressions in mode-line's :eval
> form might definitely cause problems, since the mode line is called by
> redisplay.
>


-- 
Fragen sind nicht da, um beantwortet zu werden,
Fragen sind da um gestellt zu werden
Georg Kreisler

Headaches with a Juju log:
unit-basic-16: 09:17:36 WARNING juju.worker.uniter.operation we should run
a leader-deposed hook here, but we can't yet

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