"systemd --user" and child processes fail to exit when user logs out

[Daniel Richard G.]

This concerns systemd 245.2-1ubuntu2 in Ubuntu focal.

I am using the Xfce desktop. After the user logs out from a desktop session, numerous desktop-related processes are left over. Here is a listing, taken over twenty minutes after logout:

skunk 853 0.0 0.2 18912 10300 ? Ss 17:55 0:00 /lib/systemd/systemd --user
skunk 854 0.0 0.0 103304 3496 ? S 17:55 0:00 (sd-pam)
skunk 881 0.0 0.1 8076 5324 ? Ss 17:55 0:00 /usr/bin/dbus-daemon --session --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only
skunk 970 0.0 0.1 305364 6776 ? Ssl 17:55 0:00 /usr/libexec/at-spi-bus-launcher
skunk 975 0.0 0.1 7352 4452 ? S 17:55 0:00 /usr/bin/dbus-daemon --config-file=/usr/share/defaults/at-spi2/accessibility.conf --nofork --print-address 3
skunk 979 0.0 0.1 230196 5900 ? Sl 17:55 0:00 /usr/lib/x86_64-linux-gnu/xfce4/xfconf/xfconfd
skunk 992 0.0 0.1 239704 7676 ? Ssl 17:55 0:00 /usr/libexec/gvfsd
skunk 997 0.0 0.1 378332 6444 ? Sl 17:55 0:00 /usr/libexec/gvfsd-fuse /run/user/1000/gvfs -f -o big_writes
skunk 1133 0.0 0.1 156116 5596 ? Sl 17:56 0:00 /usr/libexec/dconf-service
skunk 1139 0.0 0.1 236884 4828 ? Sl 17:56 0:00 /usr/libexec/geoclue-2.0/demos/agent
skunk 1186 0.0 0.8 59324 34792 ? S 17:56 0:00 /usr/bin/python3 /usr/share/system-config-printer/applet.py
skunk 1201 0.0 0.6 391676 25688 ? Ssl 17:56 0:00 /usr/libexec/evolution-source-registry
skunk 1224 0.0 0.8 616644 35492 ? Sl 17:56 0:00 /usr/libexec/goa-daemon
skunk 1235 0.0 0.7 708928 30512 ? Ssl 17:56 0:00 /usr/libexec/evolution-calendar-factory
skunk 1243 0.0 0.2 314744 8980 ? Sl 17:56 0:00 /usr/libexec/goa-identity-service
skunk 1271 0.0 0.7 681460 29344 ? Ssl 17:56 0:00 /usr/libexec/evolution-addressbook-factory
skunk 1302 0.0 0.1 43968 6432 ? Ss 17:56 0:00 /usr/lib/bluetooth/obexd
skunk 1322 0.0 0.2 313872 9076 ? Ssl 17:56 0:00 /usr/libexec/gvfs-udisks2-volume-monitor
skunk 1327 0.0 0.1 235684 6468 ? Ssl 17:56 0:00 /usr/libexec/gvfs-mtp-volume-monitor
skunk 1331 0.0 0.1 237956 6876 ? Ssl 17:56 0:00 /usr/libexec/gvfs-gphoto2-volume-monitor
skunk 1335 0.0 0.1 235864 5760 ? Ssl 17:56 0:00 /usr/libexec/gvfs-goa-volume-monitor
skunk 1339 0.0 0.2 316716 8800 ? Ssl 17:56 0:00 /usr/libexec/gvfs-afc-volume-monitor
skunk 1347 0.0 0.1 313684 7836 ? Sl 17:56 0:00 /usr/libexec/gvfsd-trash --spawner :1.13 /org/gtk/gvfs/exec_spaw/0
skunk 1353 0.0 0.1 162128 6028 ? Ssl 17:56 0:00 /usr/libexec/gvfsd-metadata

When a user logs out of the system, all processes associated with the login session should be terminated (barring the use of nohup(1) or the like).

If I sent a SIGINT to the "systemd --user" process above (PID 853), then all the processes promptly go away. This needs to occur on logout.

[Sebastien Bacher (seb128)]

Thank you for your bug report, do you have that user logged in from a VT or ssh maybe?
What's the output of
$ loginctl list-sessions
(log as another user to try the comment)

[Daniel Richard G. (skunk)]

This occurs whether the user logs in (through lightdm) on the console, or remotely via xrdp.

Running that command, as root, after the user (skunk) has logged in via lightdm:

    # loginctl list-sessions
    SESSION UID USER SEAT TTY
          2 0 root
         c2 1000 skunk seat0

    2 sessions listed.

After logout:

    # loginctl list-sessions
    SESSION UID USER SEAT TTY
          2 0 root
         c2 1000 skunk seat0
         c3 107 lightdm seat0

    3 sessions listed.

Even after SIGINT to "systemd --user", even after all the user processes go away, the c2 session remains present.

The output from loginctl for an xrdp login is similar. After logout:

    # loginctl list-sessions
    SESSION UID USER SEAT TTY
          2 0 root
         c1 107 lightdm seat0
         c2 1000 skunk

[Sebastien Bacher (seb128)]

Thank you for your bug report, I can't confirm the bug on focal

Using an uptodate system
- start to gdm
- login is 'userone'
- create a 'dbguser'
- logout from the 'userone' session
- ssh dbguser@

$ loginctl list-sessions
SESSION UID USER SEAT TTY
     27 1001 dbguser pts/0
     c3 124 gdm seat0 tty1

What's the output of
$ loginctl user-status skunk
for you?
(you need to ssh as another user otherwise the fact that you connect with the user to start the command is going to interfer)

[Daniel Richard G. (skunk)]

Could you try this using lightdm? It's possible that this may be a display-manager issue.

I did notice that in a different (customized) configuration of Xubuntu, the user processes still remained after logout, but then killing the "systemd --user" process resulted in the login session ending.

Anyway, here is the output you requested, in the original test environment:

# LC_ALL=C loginctl user-status skunk | cat
skunk (1000)
    Since: Fri 2020-04-10 18:40:19 EDT; 3min 11s ago
    State: closing
 Sessions: *c2
   Linger: no
     Unit: user-1000.slice
    |-session-c2.scope
    | |-1288 /usr/libexec/geoclue-2.0/demos/agent
    | `-1345 /usr/bin/python3 /usr/share/system-config-printer/applet.py
    `[e-mail]
      |-at-spi-dbus-bus.service
      | |-1131 /usr/libexec/at-spi-bus-launcher
      | `-1136 /usr/bin/dbus-daemon --config-file=/usr/share/defaults/at-spi2/accessibility.conf --nofork --print-address 3
      |-dbus.service
      | |-1042 /usr/bin/dbus-daemon --session --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only
      | |-1140 /usr/lib/x86_64-linux-gnu/xfce4/xfconf/xfconfd
      | |-1291 /usr/lib/x86_64-linux-gnu/tumbler-1/tumblerd
      | |-1302 /usr/libexec/dconf-service
      | |-1391 /usr/libexec/goa-daemon
      | `-1404 /usr/libexec/goa-identity-service
      |-evolution-addressbook-factory.service
      | `-1438 /usr/libexec/evolution-addressbook-factory
      |-evolution-calendar-factory.service
      | `-1396 /usr/libexec/evolution-calendar-factory
      |-evolution-source-registry.service
      | `-1374 /usr/libexec/evolution-source-registry
      |-gvfs-afc-volume-monitor.service
      | `-1501 /usr/libexec/gvfs-afc-volume-monitor
      |-gvfs-daemon.service
      | |-1153 /usr/libexec/gvfsd
      | |-1158 /usr/libexec/gvfsd-fuse /run/user/1000/gvfs -f -o big_writes
      | `-1509 /usr/libexec/gvfsd-trash --spawner :1.13 /org/gtk/gvfs/exec_spaw/0
      |-gvfs-goa-volume-monitor.service
      | `-1497 /usr/libexec/gvfs-goa-volume-monitor
      |-gvfs-gphoto2-volume-monitor.service
      | `-1493 /usr/libexec/gvfs-gphoto2-volume-monitor
      |-gvfs-metadata.service
      | `-1515 /usr/libexec/gvfsd-metadata
      |-gvfs-mtp-volume-monitor.service
      | `-1489 /usr/libexec/gvfs-mtp-volume-monitor
      |-gvfs-udisks2-volume-monitor.service
      | `-1484 /usr/libexec/gvfs-udisks2-volume-monitor
      |-init.scope
      | |-1017 /lib/systemd/systemd --user
      | `-1018 (sd-pam)
      `-obex.service
        `-1464 /usr/lib/bluetooth/obexd

Apr 10 18:41:21 test-ubuntu64 systemd[1017]: Stopped Indicator Application Service.
Apr 10 18:41:21 test-ubuntu64 systemd[1017]: indicator-keyboard.service: Succeeded.
Apr 10 18:41:21 test-ubuntu64 systemd[1017]: Stopped Indicator Keyboard Backend.
Apr 10 18:41:21 test-ubuntu64 systemd[1017]: Stopping Indicator Session Service...
Apr 10 18:41:21 test-ubuntu64 systemd[1017]: indicator-session.service: Succeeded.
Apr 10 18:41:21 test-ubuntu64 systemd[1017]: Stopped Indicator Session Service.
Apr 10 18:41:22 test-ubuntu64 indicator-sound[1250]: g_object_ref: assertion 'old_val > 0' failed
Apr 10 18:41:22 test-ubuntu64 systemd[1017]: pulseaudio.service: S...

[Daniel Richard G. (skunk)]

Related: LP: #1877528

[Daniel Richard G. (skunk)]

Also related: LP: #1877532

It's possible that all the lingering processes are due to a couple of misbehaving applications.

This isn't a great state of affairs (the cleanup process should not be so fragile that non-cooperative processes can stop it completely), but it might explain what's going on.

[Dan Streetman (ddstreet)]

please reopen if this is still an issue

[Daniel Richard G. (skunk)]

Yes, it is still an issue in focal. Was there an update since last year that should have addressed this?

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Jason Liu (j69liu)]

Confirmed that this is still an issue in focal.

It is only an issue if I log onto a XFCE session and then log out, these two processes stay around:
    /usr/libexec/geoclue-2.0/demos/agent
    /usr/bin/python3 /usr/share/system-config-printer/applet.py

When I remove the geoclue-2.0 from the system:
    sudo apt -y purge geoclue-2.0 --autoremove
The issue no longer shows up. I don't see neither processes hanging around any more.

I think those two are related to the two autostart programs:
    /etc/xdg/autostart/geoclue-demo-agent.desktop
    /etc/xdg/autostart/print-applet.desktop

I think in terms of workaround, two options here:
    1. remove geoclue - but the catch here is that if you autoremove, gnome dependencies may get removed, which could have unexpected outcome
    2. remove autostart files