[libvirt] [openstack-dev] [nova] The risk of hanging when shutdown instance.

[Daniel P. Berrange]

On Tue, Mar 31, 2015 at 11:37:04AM +0800, zhang bo wrote:
> On 2015/3/31 4:36, Eric Blake wrote:
> 
> > On 03/30/2015 06:08 AM, Michal Privoznik wrote:
> >> On 30.03.2015 11:28, zhang bo wrote:
> >>> On 2015/3/28 18:06, Rui Chen wrote:
> >>>
> >>>> <snip/>
> >>>
> >>>   The API virDomainShutdown's description is out of date, it's not correct.
> >>>   In fact, virDomainShutdown would block or not, depending on its mode. If it's in mode *agent*, then it would be blocked until qemu founds that the guest actually got down.
> >>> Otherwise, if it's in mode *acpi*, then it would return immediately.
> >>>   Thus, maybe further more work need to be done in Openstack.
> >>>
> >>>   What's your opinions, Michal and Daniel (from libvirt.org), and Chris (from openstack.org) :)
> >>>
> >>
> >>
> >> Yep, the documentation could be better in that respect. I've proposed a
> >> patch on the libvirt upstream list:
> >>
> >> https://www.redhat.com/archives/libvir-list/2015-March/msg01533.html
> > 
> > I don't think a doc patch is right.  If you don't pass any flags, then
> > it is up to the hypervisor which method it will attempt (agent or ACPI).
> >  Yes, explicitly requesting an agent as the only method to attempt might
> > be justifiable as a reason to block, but the overall API contract is to
> > NOT block indefinitely.  I think that rather than a doc patch, we need
> > to fix the underlying bug, and guarantee that we return after a finite
> > time even when the agent is involved.
> > 
> 
> So, may we get to a final decision? :) Shall we timeout in virDomainShutdown() or leave it to openstack?
> The 2 solutions I can see are:
> 1) timeout in virDomainShutdown() and virDomainReboot(). in libvirt.
> 2) spawn a new thread to monitor the guest's status, if it's not shutoff after dom.shutdown() for a while,
>    call dom.destroy() to force shut it down.  in openstack.

We should probably do both.

Regards,
Daniel
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