[Bug 974584] Re: Semaphores cannot be created in lxc container

[Serge Hallyn]

>From the debian bug, here is my new suggestion for a replacement for the
ischroot case in initscripts.postinst:

=============================
if ischroot; then
        # Symlink /var/run from /run
        # Note var/run is relative
        if compat_link /var/run /run; then
                # Symlink /var/lock from /run/lock
                # Note that it's really /var/run/lock
                compat_link /var/lock /run/lock

                # Symlink /dev/shm from /run/shm
                # Note that it's really /var/run/shm
		[ ! -d /run/shm ] && mkdir /run/shm
		if [ ! mountpoint -q /dev ]; then
			[ ! -d /dev/shm ] && compat_link /run/shm /dev/shm
		else
			compat_link /dev/shm /run/shm
		fi
        fi
# Host system, not a chroot.
else
=============================

So if the chroot has /dev/ bind-mounted from the host, assume they
always will, and will want /run/shm as a symlink to /dev/shm.

Otherwise if /dev/shm exists, leave it alone, because we're definately
not in debootstrap.

Otherwise, assume /dev and /run won't get cleaned up at 'shutdown'
(chroot exit) so set up *exactly* what we want to see as the end
result: /dev/shm as a symbolic link to /run/shm.

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https://bugs.launchpad.net/bugs/974584

Title:
  Semaphores cannot be created in lxc container

Status in Launchpad itself:
  Invalid
Status in “lxc” package in Ubuntu:
  Fix Released
Status in “sysvinit” package in Ubuntu:
  Triaged
Status in “lxc” source package in Precise:
  Fix Released
Status in “sysvinit” source package in Precise:
  Triaged
Status in “lxc” source package in Quantal:
  Fix Released
Status in “sysvinit” source package in Quantal:
  Triaged
Status in “sysvinit” package in Debian:
  New

Bug description:
  >>> from multiprocessing import synchronize
  >>> synchronize.Lock()
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    File "/usr/lib/python2.6/multiprocessing/synchronize.py", line 117, in __init__
      SemLock.__init__(self, SEMAPHORE, 1, 1)
    File "/usr/lib/python2.6/multiprocessing/synchronize.py", line 49, in __init__
      sl = self._semlock = _multiprocessing.SemLock(kind, value, maxvalue)
  OSError: [Errno 38] Function not implemented

  Thanks to hallyn, there's a workaround and a fix: adding this line to the container's fstab will fix the problem:
  none dev/shm tmpfs defaults 0 0

  He is updating the ubuntu template with this change.

  Original bug report description was Launchpad related (celery tests
  fail on parallel testing instances)

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