Unable to start jack (Cannot allocate memory)

Question

I want to use PulseAudio on top of jack, so I've turned pulse off and now want to start jack using qjackctl. However, this results in the following error log:

22:14:15.933 Patch Panel disabled
22:14:15.940 Reset statistics.
22:14:15.953 Changed ASLA connection.
22:14:15.970 D-BUS: Service available (org.jackaudio.service aka jackdbus).
Cannot connect to server socket err = File or directory not found
Cannot connect to server socket
jack server is not running or cannot be started
22:14:15.980 Updated visualization of ASLA connections
22:14:18.147 D-BUS: Unable to start JACK server
Cannot connect to server socket err = File or directory not found
Cannot connect to server socket
jack server is not running or cannot be started
Fri Jul 20 22:14:18 2012: Starting jack server...
Fri Jul 20 22:14:18 2012: JACK server starting in realtime mode with priority 10
Fri Jul 20 22:14:18 2012: [1m[31mERROR: Cannot lock down 82246176 byte memory area (Cannot allocate memory)[0m
Fri Jul 20 22:14:18 2012: control device hw:0
Fri Jul 20 22:14:18 2012: control device hw:0
Fri Jul 20 22:14:18 2012: [1m[31mERROR: Failed to acquire device name : Audio0 error : Cannot allocate memory[0m
Fri Jul 20 22:14:18 2012: [1m[31mERROR: Audio device hw:0 cannot be acquired...[0m
Fri Jul 20 22:14:18 2012: [1m[31mERROR: Cannot initialize driver[0m
Fri Jul 20 22:14:18 2012: [1m[31mERROR: JackServer::Open() failed with -1[0m
Fri Jul 20 22:14:18 2012: [1m[31mERROR: Failed to open server[0m
Fri Jul 20 22:14:19 2012: Saving settings to "/home/jan/.config/jack/conf.xml" ...
22:14:24.418 Cannot connect to JACK server as client - connection failed. See message dialog for details.
Cannot connect to server socket err = File or directory not found
Cannot connect to server socket
jack server is not running or cannot be started

(Several messages were in German, I did my best translating them)

The pulseaudio process is defenitely not running.

I use Ubuntu 12.04 64 bit with an NVIDIA audio card.

Answer 1

Ok, got it: I had to add myself to the group audio:

usermod -a -G audio theusername

Group membership is only updated on login, so you need to log out and in again (or just reboot).

Answer 2

The quick version: This is what I added to /etc/security/limits.conf to fix the memory lock issue; the @ symbol indicates the settings are for a group instead of a user:

 user        soft      rtprio      90
 user        soft      memlock      unlimited

 @audio      hard      rtprio      90
 @audio      hard      memlock      unlimited

 @video      hard      rtprio      90
 @video      hard      memlock      unlimited

---

There's an easy way to fix the problem "Cannot lock down 82246176 byte memory area." The memory lock is apparently very small, typically. You can check for yourself with ulimit -l or for maximum fun ulimit -a. Or maximum info, if you hate fun.

You want to configure the system to allow your user and the relevant groups to use unlimited memory.

The settings are in /etc/security/limits.conf; the file as it is doesn't do anything, but explains your options. If ulimit -l doesn't return "unlimited" after you follow my example from above, something's not right with your settings in the document.

Re: peoples' questions about Docker (or snapd, or any kind of virtualization), you may not have enough memory available flat out, or the configuration file might not be editable. Or it might work.