Sporadic un-killable jackd process

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hjhmusic
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Sporadic un-killable jackd process

Post by hjhmusic »

Hi, haven't posted in a long time. (I had been here under a different user name, but I forget what it was, so I just created a new account.)

Occasionally, I get an un-killable jack process. Everything is working fine for awhile, and then either jack stops piping audio through or it hangs when stopping the jack server in qjackctl. At this point, "ps x | grep jackd" shows me the PID, but "kill -9 <pid>" does nothing (not even as root). That is, after trying to kill it, I run the ps/grep command again and the original PID is still there.

When this happens, I can't start the jack server again through qjackctl and I have to reboot.

This is a minor annoyance as it doesn't happen very often, but it disturbs me that there could be a process running on my system that "kill" can't touch. So I would like to understand what's happening and how to resolve it without rebooting.

I'm fairly sure this occurs only for USB audio devices. I don't recall seeing this problem with the built-in PCH device (but I don't use this device very often). Also, I make it a practice always to stop jack before suspending the session, so this problem should not be the result of sleep/wake timing flubs.

Linux hjh-e431 3.13.0-96-lowlatency #143-Ubuntu SMP PREEMPT Mon Aug 29 20:56:23 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Thanks,
hjh
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