[PD] Freezes with Pd-Extended and Jack

Ivica Ico Bukvic ico at vt.edu
Fri Nov 23 23:28:12 CET 2012

See below (from the linux-audio-user list):


Re: [LAU] question about jackdmp's ability to detect its soundcard has

Could this be the difference between 1.9.8 and git version?

On Oct 29, 2012 12:10 PM, "Robin Gareus" <robin at gareus.org> wrote:

On 10/29/2012 03:55 PM, Ivica Ico Bukvic wrote:
> All,
> I noticed since upgrading to Ubuntu 12.04 that the default Jack server is
> jackdmp (v.1.9.8). Please correct me if I am wrong but my understanding
> is the smp-enabled version 2 that is being developed in parallel with 1.x
> series of regular jack.

correct. They are also API and ABI compatible.

> Either way, one of my concerns is that while in the old jack when one
> accidentally pulled the soundcard jack was trying to talk to (e.g. a USB
> soundcard), the jack would gracefully stop.

In my experience it stopped but never gracefully (ie it crashed). but
it's been a while since I used jack1.

> The new version (and this could
> be Ubuntu quirk) instead of stopping is pegged in some kind of a spinlock
> that often times locks up the machine (this may be in part since I am
> running a lowlatency kernel with audio group given priority) and at times
> keeps it operational while hogging the cpu and making the computer barely
> responsive until jackd is killed. Apps connected to jack that I tested so
> far are also stuck in a loop waiting for a response from jack (although
> could be the app's shortcoming)--jack never broadcasts a signal that it
> lost the soundcard (AFAICT). FWIW I am running jackdmp through qjackctl...
> Any thoughts on this matter would be most appreciated.

I can't reproduce this. jack2 stops the backend when the device is
disconnected. You can switch to a new backend using jack_control
(sending some Dbus messages to jackd) without re-starting jackd. No CPU
hogging here. - I'm running jack2 - aka from git.



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