[Wayland-bugs] [Bug 107672] Complete freeze if breakpoint is placed in gtk signal handler

[b***@freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=107672

Bug ID: 107672
Summary: Complete freeze if breakpoint is placed in gtk signal
handler
Product: Wayland
Version: 1.0.x
Hardware: Other
OS: All
Status: NEW
Severity: normal
Priority: medium
Component: XWayland
Assignee: wayland-***@lists.freedesktop.org
Reporter: ***@peterpall.de
QA Contact: xorg-***@lists.x.org

If you place a gdb breakpoint in in a signal handler of a wxGTK or GTK
application (for example MathCtrl::OnPaint in wxMaxima) mouse, screen and
keyboard completely freeze, if this event handler was triggered by a GUI event.
The keyboard is physically working, still, and with a bit of luck one can
switch from wayland to a text console and kill gdb from there - which returns
the wayland session to a working order.

Don't know if that is a bug or if it is completely unavoidable so I would
accept a "WONTFIX".

[b***@freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=107672

--- Comment #1 from Gunter Königsmann <***@peterpall.de> ---
Original bug report:
https://groups.google.com/forum/m/#!topic/wx-users/cgS-6YQ1Yw8

[b***@freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=107672

--- Comment #2 from Pekka Paalanen <***@gmail.com> ---
Which Wayland compositor (desktop environment) are you using?

Why is this filed as an Xwayland bug?

The terminal from where you run gdb, is it using Wayland or X11? Is the
application being debugged using Wayland or X11?

If it so happens that the app being debugged is using X11, you might be
stopping the application while it is holding Xwayland (the X11 server) hostage
(a server grab, this is perfectly normal in X11 world). This makes the X server
not process any other clients, a terminal app and even the Wayland compositor
included. So my best guess is that the app is holding an X server grab, the
Wayland compositor is doing something blocking with Xwayland, and this leads to
seemingly everything freezing.

Another option is that while the X server is grabbed, all things that use X11
are frozen, but maybe not the Wayland compositor because you say you can
sometimes switch to another VT.

If the issue really is the X11 server grab, then I'm afraid that is just how
things are intended to work. One might mitigate the issues by replacing
blocking X11 calls in the Wayland compositor with async ones, but that can be
hard.

Or, it could be something completely different. Nothing yet points to an
Xwayland bug, though.

If the application to be debugged was using Wayland, no such freeze should
happen, so that would indicate a real problem.