bug#24640: Crashes in 25.1

[Reuben Thomas]

On 9 October 2016 at 10:57, Eli Zaretskii <eliz@gnu.org> wrote:

> From: Reuben Thomas <rrt@sc3d.org>
> Date: Sun, 9 Oct 2016 08:45:08 +0100
> Cc: 24640@debbugs.gnu.org
>
>  The only efficient way to speed up debugging (or rather to make sure
>  it succeeds at all) is for you to come up with a reproducible recipe
>  and post here all the files needed for reproducing the crashes.
>
> ​That would seem to require me to bisect my .desktop and potentially post dozens of personal files, so doesn't
> seem feasible.​

If you just start a fresh session, save its desktop, then restart it,
while using the lazy-load feature, does it start normally?  Maybe all
that's needed is to do this, with no personal files involved.

​It starts normally, unfortunately.

​​

>  And the first step is
>  to stop using an optimized build, because it makes debugging much
>  harder if not impossible.
>
> I'll see if, having rebuilt from source without optimisation, the bug still fires.​

​I rebuilt with the options suggested in etc/DEBUG, and couldn't get it to crash.

​ I then tried building with -Og instead of -O0, as suggested in etc/DEBUG. Still no crash. (I ran each binary under gdb 3 times, as when it crashes it crashes more than once every 3 times I run it.) I tried building with -O2: it crashes again. Now that it is built with the same options as etc/DEBUG, except for -O2, is that more useful?

​I tried running Emacs with valgrind, but that just quickly bails out with "memory exhausted".

>  If you are willing to try the debugging yourself, there's some advice
>  in etc/DEBUG (search for "Debugging problems which happen in GC").
>
> ​I'll have a look.​

Thanks.

​Sorry: having had a look, the reconstruction of Lisp data structures looks like more than I have time for at present.

 

>  Do I understand correctly that this worked for you with Emacs 24.5?
>
> ​Yes, the identical setup loads fine in 24.5. I've never seen this sort of crash before.​

Does Emacs crash when restoring a desktop file written by Emacs 24.5,
or only when it restores files written by Emacs 25?

​Both.

--

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