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

[Richard Stanton]

>> [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?

Yes, I use AUCTeX.

> 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.

I’m talking about “Force Quit” using the OS. It aborts 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 tried leaving it for several minutes, and nothing changes. Since all I’m 
doing is typing, this seems like long enough...

>> 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.

Do you have a reference for how to do this?

Thanks.