Bug#1039878: gnome-shell: Many zombie xprop processes

[Simon McVittie]

Control: tags -1 + moreinfo

On Thu, 29 Jun 2023 at 09:36:01 +0200, Stéphane Glondu wrote:
> I noticed there are many zombie "xprop" processes on my system, whose
> parent is gnome-shell. They disappear when I restart the session, but
> then start reappearing progressively.

gnome-shell doesn't have any mentions of xprop in its source code,
so this is probably a Shell extension (which run as part of the
gnome-shell process and are just as powerful as Shell itself, but with
less experienced upstream maintainers). Please disable all extensions
and see whether the problem persists.

Based on codesearch.debian.net I'm going to guess that you probably
use gnome-shell-extension-pixelsaver, which is documented as "depends
on Xorg's `xprop` and `xwininfo` utilities", and contains at least one
suspicious use of GLib.SpawnFlags.DO_NOT_REAP_CHILD which seems likely
to cause zombie processes.

(I don't know why pixelsaver is using xprop to communicate "please don't
draw a titlebar", rather than making use of its ability to execute
arbitrary code in gnome-shell to not draw the titlebar even if the app
asked for one.)

    smcv