bug#64407: 29.0.92; Emacs hangs while editing TeX file

[Eli Zaretskii]

> From: Richard Stanton <rhstanton@berkeley.edu>
> Date: Sat, 1 Jul 2023 14:33:57 -0700
> 
> [Note: I’ve encountered the same behavior with all three release candidates 
> of 29.1, but this problem does not occur with 28.2 (with the exact same 
> init.el file).]
> 
> Intermittently, while I’m typing in a LaTeX buffer, Emacs stops responding to 
> the keyboard completely, and I have to “Force Quit” to get out. This always 
> seems to be preceded by the message
> 
> “Sorting TeX-symbol…done”
> 
> appearing in the mini buffer.

I don't see such a message in tex-mode.el.  Are you using add-on
packages for editing LaTeX? if so, which ones?  I see TeX-PDF-mode and
TeX-source-correlate-mode in your bug report -- what are those?

And what does "Force Quit" mean in terms of Emacs?  Is this an Emacs
command or an OS command?  And what does it do to Emacs? do you still
have the same session running after it, or does it abort Emacs?

Also, how long did you wait before using "Force Quit"? could it be
that Emacs is doing something that takes a long time?

> I’ve noticed that the title changes if I mouse click on a  different buffer, 
> so Emacs seems not to be completely dead, but the cursor never appears in the 
> new buffer and I can’t actually do anything so it (almost) might as well be.
> 
> I’ve tried finding a simple, repeatable way to get this to happen, but have 
> so far been unsuccessful. I’d be happy to investigate further if anyone can 
> tell me how to do so.

One way of investigating is to attach a debugger to Emacs when it
stops responding, and show the backtrace from all the threads.