Public bug reported:

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.

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) {
                    }
                }
            );
```

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.

** Affects: gnome-shell
     Importance: Unknown
         Status: Unknown

** Affects: oem-priority
     Importance: Undecided
         Status: New

** Affects: gnome-shell (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: oem-priority originate-from-2017628 somerville

** Tags added: oem-priority originate-from-2017628 somerville

** Bug watch added: gitlab.gnome.org/GNOME/gnome-shell/-/issues #6698
   https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/6698

** Also affects: gnome-shell via
   https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/6698
   Importance: Unknown
       Status: Unknown

-- 
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Desktop Bugs, which is subscribed to gnome-shell in 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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