Do not explicitly start daemon in start-pulseaudio-x11

[Martin Pitt]

Binary package hint: pulseaudio

Right now, pulseaudio is started about three or four times during boot [1], which wastes precious cycles.

For example, /etc/xdg/autostart/pulseaudio.desktop runs /usr/bin/start-pulseaudio-x11, which is a shell script which in turn calls pulseaudio (which exits after a while since it is already running), and then loads three additional modules with pactl.

Can these three modules just go into /etc/pulse/default.pa, and the autostart desktop and start-pulseaudio-x11 be dropped?

[1] http://people.canonical.com/~pitti/bootcharts/daniel-lucid-20100127-1.png

[Martin Pitt (pitti)]

Luke, can you please review this idea? I'm fine to implement this, but I'd like to get some review on that first. Thanks!

[Daniel T Chen (crimsun)]

Please note the existing comment in /etc/pulse/default.pa:

"# X11 modules should not be started from default.pa so that one daemon
# can be shared by multiple sessions."

What are the implications on, e.g., user-switching with user A logged
in from multiple terminals?

[Martin Pitt (pitti)]

I saw the comment, but I cannot make much sense of it. If I log in twice, then I'd get two sets of pactl, each loading the same modules. If having an x11 module loaded with several user sessions is a problem, how does it make a difference whether it's loaded by pactl or from default.pa?

Or does this apply to the system-wide daemon mode? In that case, doesn't that use /etc/pulse/system.pa instead of default.pa?

[Martin Pitt (pitti)]

Oh, I see the difference: without the autostart file, the module would only be loaded once and for all. start-pulseaudio-x11 additionally submits the $DISPLAY.

That's still going to break with multiple user sessions either way:

 (1) with default.PA the "current" $DISPLAY would be the first session of that user, ever

 (2) with start-pulseaudio-x11 the "current" $DISPLAY will always be the session that was started last, and previous sessions would lose the module (assuming that this actually reloads the module); OTOH, if trying to load an already loaded module is a no-op, then it should be no different to (1)?

If PA really wants to do proper support for multiple sessions with one daemon, it needs to add a /usr/lib/ConsoleKit/run-seat.d/ script.

[Martin Pitt (pitti)]

So, due to a bug in X.org/console handling/whatever I can't currently start two X.orgs at the same time, so I'm unable to test this myself. If a second X session for the same user would result in those modules being loaded twice (one for each $DISPLAY), this could indeed work.

One remaining thing that could be dropped from start-pulseaudio-x11 is the /usr/bin/pulseaudio --start. It's already running at that time anyway (and thus just wastes a process and cycles), and even if not, pactl will trigger it itself (due to the library auto-spawning the daemon).

[Martin Pitt (pitti)]

Daniel, saw your branch and merge proposal. Thanks!

[Launchpad Janitor (janitor)]

This bug was fixed in the package pulseaudio - 1:0.9.22~0.9.21+stable-queue-32-g8478-0ubuntu2

---------------
pulseaudio (1:0.9.22~0.9.21+stable-queue-32-g8478-0ubuntu2) lucid; urgency=low

  * debian/01PulseAudio: Use su(1) instead of sudo(8)
    (LP: #489144, #498980).
  * debian/patches/series: To trim the startup time, don't lazy-load
    sounds by not applying 0005-load-sample-dir-lazy.patch.
  * 0091-dont-load-cork-music-on-phone.patch: Refresh.
  * 0057-load-module-x11-bell.patch: Don't explicitly load the daemon
    since it will autospawn if necessary, and if the system or user
    configuration has autospawn disabled it breaks that semantics
    (LP: #513120).
 -- Daniel T Chen <email address hidden> Fri, 29 Jan 2010 14:37:52 -0500