[H-GEN] Systemd killing processes after logout

[P Newman]

On 06/06/16 10:24, Russell Stuart wrote:
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> At the last Humbug we discussed in new feature in systemd - it now
> kills all background processes on logout, including those run by nohup,
> screen, tmux, mosh and so on.  This new behaviour arrived in Debian
> unstable on May 23.
>
> At the meeting there was furious agreement this was insane, (except
> from Clinton, who defended it - but then he defended binary logs when
> they first came out so this wasn't unexpected).  The question most
> interesting to me was WTF? - with the W standing for "why".  'nix has
> had a mechanism for do this for as long as I can remember - all
> descendent processes of the login process is sent a HUP signal when it
> exits.  It was simple, robust mechanism and had worked well back when
> we had 100's students learning to use computers for the first time on a
> single timesharing machine.  So why this new one?
>
> I knew [0] it was because on Desktop's now it's the fashion to have
> background services are started by via RPC (remote procedure call) sent
> to a background daemon, and the background daemon was evidently not
> started by the login shell.  I assumed it was a global background
> process, but Clinton insisted a separate background RPC daemon was
> started for each login session.
>
> Turns out we are both 1/2 right.  Clinton is right - a separate RPC
> background daemon is started for each login session, but for some
> reason is *not* a descendent of the login process (lightdm in my case).
>   So on my laptop I have two trees of processes for my login:
>
>      systemd,1                    systemd,1
>      `-systemd,2356               `-lightdm,1246
>        |-(sd-pam),2362             `-lightdm,2347
>        |-dbus-daemon,2383            `-lxsession,2375
>        |-dconf-service,2880            |-lxpanel,2440
>        |-evolution-addre,2914          |-lxpolkit,2439
>        | |-evolution-addre,2952        |-openbox,2436
>        |-evolution-calen,2889          | |-evolution,2858
>        | |-evolution-calen,2896        | `-iceweasel,2749
>        | |-evolution-calen,2905        |-pcmanfm,2442
>        | |-evolution-calen,2920        |-pidgin,2443
>        |-evolution-sourc,2863          |-ssh-agent,2409
>        |-gconfd-2,2610
>        |-gnome-terminal-,2691
>        | |-bash,2697
>        | |   `-pstree,3639
>        |-goa-daemon,2550
>        |-goa-identity-se,2561
>        |-gvfs-afc-volume,2532
>        |-gvfs-goa-volume,2546
>        |-gvfs-gphoto2-vo,2541
>        |-gvfs-mtp-volume,2537
>        |-gvfs-udisks2-vo,2515
>        |-gvfsd,2420
>        |-gvfsd-fuse,2425
>        |-gvfsd-metadata,2868
>        `-gvfsd-trash,2498
>
> I have no idea why they designed it that way - in fact it seems utterly
> inexplicable.  But it meant when the user logged out the cleanup
> process wasn't simple. With complexity comes bugs, and so often
> background daemons were left running when a GUI user logged out.  The
> systemd guys decided the solution wasn't to fix the design, it was to
> use a bigger hammer that impacted not just the GUI users who had the
> original problem - but all of the headless systems maintained by
> sysadmins who, if they have a process running on logout are almost
> certainly wanted it to remain running.
>
> It's mostly developers who run GUI's on Debian (the unwashed masses
> tend to use something like Ubuntu), and it was Debian developers who
> thought this change was a good idea.  But when it's all said and done
> Debian's main users are the thousands if not millions of headless
> servers maintained by those sysadmin's.  The howls of protest from them
> started 3 days after the change hit unstable, and ramped up rapidly.
> So it's not surprising the Debian systemd packagers have now uploaded a
> new version reverting this particular "improvement".
>
> But this does mean the original problem it was put in to fix remains a
> problem in Debian.  In fact it has hit me - I've seen it those
> duplicate copies of Gnome services running on my laptop from time to
> time.  I had wondered who they got started.
>
>
> [0] https://github.com/systemd/systemd/issues/2900
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I've passed the stage where systemd's complexity has made it more of a 
hassle than a benefit, so much of it is unused on any system I have. 
I've started to migrate to non systemd installs now and life is so much 
easier. I don't use any desktop environments though.