On Thu, Sep 29, 2011 at 10:12:17PM -0500, Serge E. Hallyn wrote:
Quoting Daniel P. Berrange (berrange@redhat.com):
Nova (openstack) calls libvirt to create a container, then periodically checks using GetInfo to see whether the container is up. If it does this too quickly, then libvirt returns an error, which in libvirt.py causes an exception to be raised, the same type as if the container was bad. lxcDomainGetInfo(), holds a mutex on 'dom' for the duration of its execution. It checks for virDomainObjIsActive() before
On Wed, Sep 28, 2011 at 02:14:52PM -0500, Serge E. Hallyn wrote: trying to use the cgroups.
Yes, it does, but
lxcDomainStart(), holds the mutex on 'dom' for the duration of its execution, and does not return until the container is running and cgroups are present.
No. It calls the lxc_controller with --background. The controller main task in turn exits before the cgroups have been set up. There is the race.
The lxcDomainStart() method isn't actually waiting on the child pid directly, so the --background flag ought not to matter. We have a pipe that we pass into the controller, which we wait on for a notification after running the process. The controller does not notify the 'handshake' FD until after cgroups have been setup, unless I'm mis-interpreting our code Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|