Mainloop debugging tool idea

[Bastien Nocera <hadess hadess net>]

Heya,

I had some problems with gnome-shell's responsiveness on particularly
dodgy hardware, and was wondering whether the shell was actually
blocking at any point.

Came the idea of using of watchdog thread, based on the mainloop, which
would check for how long the mainloop was running a particular
iteration, and have to dump a backtrace if the main loop was blocking on
a particular task for more than X amount of time.

Does anyone have code like that available? If not, where would one plug
that code into the main loop code in gmain.c?

This would make testing problems like the ones split off from:
https://bugzilla.gnome.org/show_bug.cgi?id=687362
much easier.

Cheers