[pulseaudio-discuss] Remaining PA process after X logout

[Tanu Kaskinen]

On Mon, 2018-02-26 at 10:20 +0100, Takashi Iwai wrote:
> On Mon, 26 Feb 2018 10:12:44 +0100,
> Tanu Kaskinen wrote:
> > 
> > On Sat, 2018-02-24 at 11:17 +0100, Takashi Iwai wrote:
> > > Hi,
> > > 
> > > we've stumbled on a long-standing issue with PA, namely, PA fails to
> > > start after relogin quickly.  The details and discussions are found in
> > >   https://bugzilla.suse.com/show_bug.cgi?id=1052437
> > > 
> > > In short, the problem is that the session management removes
> > > $XDG_RUNTIME_DIR (/run/users/*) after logout while PA remains running.
> > > This leaves also the ESD socket in /tmp/esd-$uid, too.  When re-login,
> > > a new PA process is kicked off because the old socket in /run/user/*
> > > is gone.  Then it hits with the existing /tmp/esd-$uid, considering as
> > > a fatal error, hence it aborts.
> > > 
> > > 
> > > Now the primary question is what's the right approach to fix this.
> > > I guess the best would be to kill PA properly at each X session logout
> > > instead of self-killing after idle.  Then where's the best place to put
> > > that?
> > 
> > Does suse use systemd to manage the pulseaudio user service?
> 
> It's started by XDG autostart.

So the good old autospawning mechanism. The XDG autostart script
doesn't (any more) explicitly start pulseaudio, it just runs some pactl
commands that as a side effect start the pulseaudio daemon if
autospawning is enabled in client.conf.

> > If not,
> > what component does remove $XDG_RUNTIME_DIR?
> 
> This is done by logind and pam_systemd, I suppose.

If KDE doesn't remove the runtime dir, then I'm out of theories about
why this only happens with KDE...

> > It would seem logical that
> > the same component would terminate services that break if their sockets
> > are removed.
> 
> systemd *can* clean up the whole user-space (e.g. add
> KillUserProcess=yes in /etc/logind.conf), but it's not enabled as
> default.  There are users and services that want to keep running the
> sfuff after logout (think of some computing task).  So forcibly
> enabling this just for PA doesn't sound like a right solution,
> either.

I agree.

> > What about fedora? I somehow would expect fedora to be eager to adopt
> > the socket activation feature in pulseaudio that has been available for
> > a long time already.
> > 
> > If you're using pulseaudio under systemd, it seems weird if all user
> > services don't get terminated on logout.
> 
> I guess they would hit the same issue.  But maybe there can be some
> workaround.

I don't think the same issue would affect pulseaudio if it was under
systemd control, unless the user instance of systemd keeps running for
longer than logind keeps the runtime dir around. I'd be very surprised
if that was the case. I had a look at systemd documentation, which
confirmed to me that when the user instance of systemd shuts down, it
will stop all services that haven't explicitly requested not to be
stopped.

-- 
Tanu

https://liberapay.com/tanuk
https://www.patreon.com/tanuk