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#1 2016-02-06 13:04:57

jmx
Member
Registered: 2016-02-06
Posts: 19

jack2-dbus no longer starts

Hello,

I was using jack2-dbus occasionally to do some audio recording / synthesis work with Ardour, Pure Data, SuperCollider and the like, using PulseAudio for my day to day desktop work. I never had any issues with this setup.

But, when I tried to start jack today, I ran into these errors:

$ jack_control start
--- start
ERROR:dbus.proxies:Introspect error on :1.52:/org/jackaudio/Controller: dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
DBus exception: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.

Off the possible causes, I think a timeout might be the most likely cause, as it takes ~20 seconds for each of the two messages to appear.

I did a pacman -Syu this morning and rebooted afterwards, so I think I'm on all latest software.

Does anyone have any idea, why I can't start jack anymore? Is this a dbus or a jack issue?

Best,
jmx

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#2 2016-02-07 11:33:47

jmx
Member
Registered: 2016-02-06
Posts: 19

Re: jack2-dbus no longer starts

I did some more tests today, and I think JACK is unable to grab the soundcard from PulseAudio. At least I can get jack to start when I select the "dummy" driver (instead of ALSA, what it used to use). As soon as I change the driver back to ALSA and try to restart JACK, it fails again with the above dbus error.

Have there been some changes to how one should configure the PulseAudio / JACK configuration since Pulse's 8.0 update? I used to just follow loosely the steps in https://wiki.archlinux.org/index.php/JA … mple_setup to make JACK and Pulse cooperate and it just worked.

When the problems started yesterday, it was my first time trying to start JACK since the PA 8.0 update, so suspect some changes on Pulse's side that make my configuration fail? Any more hints how to investigate further?

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#3 2016-02-07 13:00:45

ooo
Member
Registered: 2013-04-10
Posts: 1,637

Re: jack2-dbus no longer starts

If you think pulseaudio update is causing your issue, you could try downgrading it from pacman cache or ALA. I didn't see anything on pulseaudio changelog that would obviously cause issues with jackdbus though.

It's also possible that there's something wrong with dbus on your system, but then you'd probably have some other issues also.

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#4 2016-02-07 14:12:59

jmx
Member
Registered: 2016-02-06
Posts: 19

Re: jack2-dbus no longer starts

I just downgraded libpulse, pulseaudio and pulseaudio-jack to 7.1-3, which I still had in my pacman cache, and did a reboot. Plain desktop audio works fine, as expected, but jack still doesn't start.

I copied some more log messages I got from Qjackctl. Here it seems that JACK was able to aquire the card. But the explicit ERROR messages still point towards dbus:

Sun Feb  7 15:02:32 2016: Starting jack server...
Sun Feb  7 15:02:32 2016: JACK server starting in realtime mode with priority 10
Sun Feb  7 15:02:32 2016: self-connect-mode is "Don't restrict self connect requests"
Sun Feb  7 15:02:32 2016: Acquired audio card Audio0
Sun Feb  7 15:02:32 2016: creating alsa driver ... hw:NVidia|hw:NVidia|512|2|48000|0|0|nomon|swmeter|-|32bit
Sun Feb  7 15:02:33 2016: configuring for 48000Hz, period = 512 frames (10.7 ms), buffer = 2 periods
Sun Feb  7 15:02:33 2016: ALSA: final selected sample format for capture: 32bit integer little-endian
Sun Feb  7 15:02:33 2016: ALSA: use 2 periods for capture
Sun Feb  7 15:02:33 2016: ALSA: final selected sample format for playback: 32bit integer little-endian
Sun Feb  7 15:02:33 2016: ALSA: use 2 periods for playback
Sun Feb  7 15:02:38 2016: ERROR: JackPosixProcessSync::LockedTimedWait error usec = 5000000 err = Connection timed out
Sun Feb  7 15:02:38 2016: ERROR: Driver is not running
Sun Feb  7 15:02:38 2016: ERROR: Cannot open client name = dbusapi
Sun Feb  7 15:02:38 2016: ERROR: failed to create dbusapi jack client
Sun Feb  7 15:02:38 2016: ERROR: Unknown request 4294967295
Sun Feb  7 15:02:38 2016: ERROR: CheckSize error size = 0 Size() = 12
Sun Feb  7 15:02:38 2016: ERROR: CheckRead error

How would those "other issues" you've mentioned manifest themselves, if it was a dbus problem? I'd suspect other processes failing "randomly"?
I did not face any other problem, yet. The JACK problem is the only issue I have on my machine.

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#5 2016-02-07 15:11:15

jmx
Member
Registered: 2016-02-06
Posts: 19

Re: jack2-dbus no longer starts

Ok, I'm getting somewhere!

It seems to having to do with the kernel. While I was grep'ing through my pacman cache, I noticed that the update to kernel 4.4 was around the same time as my first suspect pulseaudio. So downgraded to kernel 4.3.3-3 and now I'm able to start JACK again.

For the moment, I have a working system again. But I still don't know who is the culprit. And I dislike the idea of having to stay on an unsupported kernel for a longer time, so I'd like to help with a future-safe solution to this issue. So, it seems that I should file a bug somewhere... against the kernel? Against JACK?

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#6 2016-02-07 15:28:09

jmx
Member
Registered: 2016-02-06
Posts: 19

Re: jack2-dbus no longer starts

For the record, here's a bug report for this issue that I just filed against jack2-dbus:
https://bugs.archlinux.org/task/48073

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#7 2016-02-07 19:03:27

ooo
Member
Registered: 2013-04-10
Posts: 1,637

Re: jack2-dbus no longer starts

jmx wrote:

How would those "other issues" you've mentioned manifest themselves, if it was a dbus problem? I'd suspect other processes failing "randomly"?
I did not face any other problem, yet. The JACK problem is the only issue I have on my machine.

Are other programs failing to start, or something not functioning properly?
You could also check journal (or start applications from command line and check the output) for any errors that could be related to this issue.

If everything else is working fine with 4.4 kernel apart from jackdbus, this is probably a jack specific problem.

You could use linux-lts kernel until the problem is resolved.

Since this is a relatively rare user case it might be a good idea to seek help from/report the issue to jack developers also (they're on github).

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#8 2016-02-08 08:07:46

jmx
Member
Registered: 2016-02-06
Posts: 19

Re: jack2-dbus no longer starts

No, I did not come across any other issue with the 4.4 kernel, yet.

I just reported the issue to the JACK devs as well, see https://github.com/jackaudio/jack2/issues/186 .

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