bug#61436: Emacs Freezing With Java Files

[Robert Weiner]

Jens wrote:

> That always freezes Emacs (29 and master) even before it has a chance to
> display P1.java.  The freeze happens in function
> `c-get-fallback-scan-pos', where the while loop inf-loops, BUT:
>
> If you uncomment the line setting `hkey-init' to nil in init.el and
> repeat: No freeze.

As you note above, the infinite loop is coming from a Lisp function in Emacs core, not from Hyperbole.  A Hyperbole setting may help you to see a state reached in that function that you otherwise would not, but it is not a Hyperbole bug; it is an unhandled state outside of Hyperbole.  When the issue is found, we will have to work around it in Hyperbole since we support Emacs versions back to 27.1 but that is another matter.  Thanks for pointing it out.

-- rsw

On Wed, Oct 11, 2023 at 3:29 AM Mats Lidell <mats.lidell@lidells.se> wrote:

Hi Jens,

Thanks for the report. Seems non trivial.

> Jens Schmidt writes:
> Jens Schmidt <jschmidt4gnu@vodafonemail.de> writes:
>
> >   Ensure package "hyperbole" is installed.  (Its only role in this
> >   issue seems to be a "background load generator", but I'm not 100%
> >   sure here.)
>
> The second part above is not true!  Hyperbole mode is the culprit,
> unless proven otherwise.  Here is a 100%-freezing reproducer (with
> P1.java as from the initial post):
>
> ------------------------- init.el -------------------------
> (require 'package)
> (add-to-list 'package-archives
>            '("melpa" . "https://melpa.org/packages/"))
> (add-to-list 'package-archives
>            '("gnu" . "https://elpa.gnu.org/packages/"))
> (package-initialize)
> ;(setq hkey-init nil)
> (hyperbole-mode 1)
> ------------------------- init.el -------------------------
>
> Execute Emacs as:
>
>   ./src/emacs -Q -l ~/tmp/init.el +181 ~/tmp/P1.java
>
> That always freezes Emacs (29 and master) even before it has a chance to
> display P1.java.  The freeze happens in function
> `c-get-fallback-scan-pos', where the while loop inf-loops, BUT:
>
> If you uncomment the line setting `hkey-init' to nil in init.el and
> repeat: No freeze.

I have tried to recreate the freezing (with 29.1 running docker) and I don't
see the exact same behavior. For me P1.java is displayed and there us no
freeze but when I try to go to top or bottom of file it freezes and I have to
hit C-g. After that it seems to work. This is just an observation. There can
be more things affected of course.

I have tried both with the hyperbole stable and devel packages and get the
same behavior.

Note: I don't know what P1.java means here. I have picked a java file at
random that I had on my machine that is large. Is P1.java a specific file that
has been shared earlier?

> Not sure how to continue here - since this is a GNU ELPA package, it can
> be further handled on Emacs debbugs, no?  Mats, Bob?

Hyperbole has its own tracker.

https://debbugs.gnu.org/cgi/pkgreport.cgi?package=hyperbole

%% Mats