bug#35961: 27.0.50; Sometimes frame freezes and stops updating (almost entirely)

["Basil L. Contovounesios" <contovob@tcd.ie>]

Dmitry Gutov <dgutov@servers.com> writes:

> The windows' contents stay almost unchanged (with the exception of some
> visual glitches) in response to most commands I issue. Some weird
> effects can remain, like blinking cursor(s).
>
> It's not a Emacs freeze, because I can switch to another application and
> back, and *then* the contents become updated (and still frozen
> afterwards), so I can issue a command, switch back and forth and see the
> result.
>
> It happens randomly with no particular reproduction scenario. I can
> never see it for a week or two, and then it happens 2-3 times a day. The
> only thing in common I remember is there's usually an
> *rspec-compilation* buffer shown (a third-party compilation major mode).
> It often contains long lines, and while compilation is running, it
> enacts a certain strain on our display engine.
>
> What I tried:
>
> - Evaluating
>
>     (modify-all-frames-parameters '((inhibit-double-buffering . t)))
>
>   => the frozen frame does not get better.
>
> - Creating a new frame with 'C-x 5 2'. The result is a responsive frame,
>   all the while the previous one is in that weird state. Further, the
>   said previous frame can start updating the area of the screen where
>   the new frame was initially displayed. That area doesn't change as I
>   move/resize the new frame.
>
> It's not a new problem, I've been seeing it for months on and off. It's
> just weird and infrequent enough that I've held off from reporting.

I use xmonad as my (tiling) window manager, and FWIW your description
sounds almost identical to what happens to my Emacs session (master and
emacs-26, with or without -Q) when I type C-z (suspend-frame), which in
turn calls iconify-or-deiconify-frame.

-- 
Basil