Quoting Daniel P. Berrange (berrange@xxxxxxxxxx):
> On Wed, Sep 28, 2011 at 02:14:52PM -0500, Serge E. Hallyn wrote:
> > 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
> trying to use the cgroups.
>
> 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.
Yup, now that you mention it, I do see that. So this shouldn't be
happening. Can't explain it, but copious fprintf debugging still
suggests it is :)
Is it possible that vm->def->id is not being set to -1 when it is
first defined, and I'm catching it between define and start? I
would think that would show up as much more broken, though I'm
not seeing where vm->def->id gets set to -1 during domain definition.
Well, I'll keep digging then. Thanks for setting me straight on
the mutex!
> Similarly when we delete the cgroups, we again hold the lock
> on 'dom'.
>
> Thus any time viDomainObjIsActive() returns true, AFAICT, we have
> guaranteed that the cgroup does in fact exist.
>
> So can't see how control gets to the 'else' part of this
> condition if the cgroups don't exist like you describe.
>
> if (!virDomainObjIsActive(vm) || driver->cgroup == NULL) {
> info->cpuTime = 0;
> info->memory = vm->def->mem.cur_balloon;
> } else {
> if (virCgroupForDomain(driver->cgroup, vm->def->name, &cgroup, 0) != 0) {
> lxcError(VIR_ERR_INTERNAL_ERROR,
> _("Unable to get cgroup for %s"), vm->def->name);
> goto cleanup;
> }
>
>
> What libvirt version were you seeing this behaviour with ?
0.9.2
thanks,
-serge
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