** Description changed:
+ [ Impact ]
+
If gnome-shell is launched directly instead of launched through gnome-
session, the process spawning `ibus-daemon` might cause deadlock and
unable to start the graphics.
Since `ibusManager.js` checks whether service
`org.freedesktop.IBus.session.GNOME.service` exists. In our case with
Ubuntu ubiquity, we've turned off `gnome-session.service` so that the
check failed and gnome-shell spawns `ibus-daemon` after the check.
+
+ [ Test case ]
+
+ - In a terminal launch
+ - env XDG_RUNTIME_DIR=/tmp/nested-runtime \
+ dbus-run-session gnome-shell --nested --wayland
+ - The shell should start without hanging
+ - Repeat this multiple times and ensure it works reliably
+
+ [ Regression potential ]
+
+ - Shell (and or its extensions) may not be able to spawn child processes
+ - Applications launched by the shell may inherit the rlimits of mutter
+
+ ---
I tried using gdb to gnome-shell and discovered it's hanging in a child
process spawning `ibus-daemon`, but is still in child_setup of
`Glib.spawn_async` function:
```
root@dell-desktop:/home/oem# cat /tmp/log
== Stack trace for context 0x5584da793180 ==
#0 5584dbd2d478 i resource:///org/gnome/shell/misc/ibusManager.js:119
(2776aa47bfb0 @ 12)
#1 5584dbd2d3a8 i resource:///org/gnome/shell/misc/ibusManager.js:114
(2776aa47bf60 @ 426)
#2 5584dbd2d308 i resource:///org/gnome/shell/misc/ibusManager.js:90
(2776aa47bec0 @ 162)
#3 5584dbd2d268 i self-hosted:689 (34e3dc212650 @ 15)
```
which is, in ibusManager.js:
```
- const [success_, pid] = GLib.spawn_async(
- null, cmdLine, env,
- GLib.SpawnFlags.SEARCH_PATH |
GLib.SpawnFlags.DO_NOT_REAP_CHILD,
- () => {
- try {
- global.context.restore_rlimit_nofile(); # <- here
- } catch (err) {
- }
- }
- );
+ const [success_, pid] = GLib.spawn_async(
+ null, cmdLine, env,
+ GLib.SpawnFlags.SEARCH_PATH |
GLib.SpawnFlags.DO_NOT_REAP_CHILD,
+ () => {
+ try {
+ global.context.restore_rlimit_nofile(); # <- here
+ } catch (err) {
+ }
+ }
+ );
```
Further code tracing found out that the deadlock is not during the
execution of the function (`restore_rlimit_nofile`) but the access to
the GObject (probably `global.context`).
Currently my propose to work around this issue is to add a 5 second
`setTimeout` to the caller of `_spawn` function in `ibusManager.js`.
I've lost debugging information but I can try reproducing the issue and
give the backtrace from gdb if needed.
--
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Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2019776
Title:
If gnome-shell is started directly (instead of through gnome-session),
it might deadlock with no output to the screen
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