[Jack-Devel] jackdbus process eats two CPU cores for hours on end

[John Rigg]

On Sun, Dec 04, 2016 at 04:26:14AM +0000, Thomas Howe wrote:
> Hi all,
> 
> I'm having a problem with the jackdbus process; after some hours it starts
> maxing out two of my four CPU cores, which in turn causes xruns when
> running apps. It looks like other people have found the same problem, but
> no solutions.
> 
> Here's a video of this happening:
> https://drive.google.com/open?id=0B2eROo5JatB4eHZweUtROTduSWc
> I cut the important bits out and sped it up. It shows me starting jack via
> QJackCtl with a monitor of the log file and QJackCtl's messages in the
> first section, the processor spike in the second, an xrun in the third, and
> the processors returning to normal in the fourth. There's a clock at the
> bottom left corner of the screen.
> 
> I'm running Arch with the Linux 4-8-4.1-ARCH (x86_64) kernel. Let me know
> what other information would be useful! I can't figure out how to even
> start debugging this.

I couldn't watch the video here ('format not supported' error), but for
how long and at what sample rate are you trying to run JACK? IIRC
jack transport stores sample frame count as a 32-bit unsigned integer.
At 48kHz that's a little over 24hr before it hits the end of the counter.

John