bug#26097: Segmentation fault due to missing faces in face_cache.

[Eli Zaretskii <eliz@gnu.org>]

[Please keep the bug address on the CC list.]

> From: Codrut Gusoi <codrut.gusoi@gmail.com>
> Date: Mon, 20 Mar 2017 14:16:29 +0200
> 
> I've tried watching the `used` count with `watch -l` and there is no
> place where the font cache shrinks for the current frame. I believe
> what I experineced previously was the `used` count from different
> frames (since I added a breakpoint but did not look at the frame
> address).

For the bug you describe to happen, the 'used' count of a frame's face
cache _must_ be reset to zero at some point.  There simply isn't any
other way to "lose" faces from the cache.  So if you don't see that,
it means you didn't succeed to reproduce the problem.

> Have you managed to reproduce it locally?

No.

> If not, what do you say I set up a VM in AWS and give you the IP and
> login details to take a look.

That could work if there's a more-or-less reliable recipe for
reproducing the problem.  Is there?

If there is not recipe, I won't be able to investigate the path to
disaster, and when the segfault happens, it's already too late.