[Bug 491329] [NEW] jackd cannot be started in realtime mode on Karmic if there is not enough free space in /dev/shm

[Holger Arnold]

Public bug reported:

When trying to start jackd in realtime mode with memory locking enabled,
at least on my system, it crashes with a "Bus error" without printing
any useful error message.  What happens seems to be the following:

1. Ubuntu mounts a tmpfs file system in /dev/shm with a size of 50% of the main memory size.  My system has only 512MB RAM, so my /dev/shm is 256MB.
2. /dev/shm is also used by Pulseaudio, which seems to allocate ~64MB for every client.  On my system this means that most of the time there is no free space in /dev/shm.  Moreover, even after shutting down Pulseaudio, there are pulse-shm-* files left in /dev/shm.
3. When started in realtime mode with memory locking enabled, jackd attempts to allocate ~130MB shared memory without checking for free space.  This fails and jackd crashes with a bus error.

I don't know exactly how the /dev/shm file system works or how
Pulseaudio uses it, but the following solves the problem:

1. Make shure that Pulseaudio is not running.  I use the Fluxbox WM for audio, so when I kill Pulseaudio, it is not automatically restarted; I don't know how this can be done when running Gnome.
2. Clean up /dev/shm by deleting the files left over by Pulseaudio.
3. Start jackd in realtime mode with memory locking enabled.

I would expect the following behavior:

1. jackd should tell the user that there is not enough shared memory available and shut down cleanly instead of crashing.
2. There should be no files left over by Pulseaudio when it is not running.

ProblemType: Bug
Architecture: i386
Date: Wed Dec  2 11:56:48 2009
DistroRelease: Ubuntu 9.10
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release i386 (20091028.5)
Package: jackd 0.116.1-4ubuntu2
ProcEnviron:
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-15.50-generic
SourcePackage: jack-audio-connection-kit
Uname: Linux 2.6.31-15-generic i686

** Affects: jack-audio-connection-kit (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: apport-bug i386

-- 
jackd cannot be started in realtime mode on Karmic if there is not enough free space in /dev/shm
https://bugs.launchpad.net/bugs/491329
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.

-- 
ubuntu-bugs mailing list
ubuntu-bugs at lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs