On Wed, 08 Jun 2016, Dan Purgert wrote:

> This was in the comments of the article on lwn (sorry, I forget who
> linked it on the mailing list). I'm honestly not sure how "true" it is,
> but it seems to coincide with what else I've been reading.
>
> 1. In the beginning there was there login. Every process started after
> login was a child of it, the kernel used a very simple process to track
> those children and so it was easy to clean up on logout.
>
> 2. Then X and xdm replaced login, but every process was a child of xdm,
> and cleaning up on logout remained simple.
>
> 3. Then there was GNOME, and gdm, and later gdm spawned corba. Things
> were rapidly getting more complex, but nonetheless everything was a
> process child of gdm and so cleaning up on logout was till simple.
>
> 4. GNOME moves to dbus.
>
> 5. systemd takes over dbus.
>
> 6. systemd takes over session management - primarily via logind.
>
> 7. GNOME immediately adopts logind, causing much angst on Debian because
> it meant the default desktop required you to use systemd.
>
> 8. GNOME starts uses dbus to lazily start services.
>
> 9. systemd starts dbus under a separate process tree (the one under
> systemd --user, as opposed to the one started by gdm).
>
> 10. GNOME notices if the user logs in twice, they start services such as
> the evolution-address-book twice. Seems inefficient. They share services
> between two login sessions. For some services.
>
> 11. Consequently keeping track of what session owns what process becomes
> hard. Some things aren't killed properly when the sessions logout. Since
> logind is tracking the sessions, seems like a good idea to make it the
> systemd mob's problem. KillUserProcesses is implemented, and GNOME's
> problem is solved.
>
> 12. But no one is turning KillUserProcess on so GNOME sessions are still
> leaving services running. So systemd-230 changes it to default to be on.

And some news:

13. Debian removes logind's 'KillUserProcesses' by default *at build*
https://anonscm.debian.org/cgit/pkg-systemd/systemd.git/commit/?id=c11c9a4601ec0dbfb8a64e2c1c0309a590ab838b

So if the above is true then GNOME will leave services running?

ciao