The associated bug says this is probably a qemu bug, so I think we should rephrase that to "we need to start thinking about how to make sure upstream changes don't break nova".
Michael On Wed, Jul 9, 2014 at 7:50 AM, Joe Gordon <joe.gord...@gmail.com> wrote: > > On Thu, Jun 26, 2014 at 4:12 AM, Daniel P. Berrange <berra...@redhat.com> > wrote: >> >> On Thu, Jun 26, 2014 at 07:00:32AM -0400, Sean Dague wrote: >> > While the Trusty transition was mostly uneventful, it has exposed a >> > particular issue in libvirt, which is generating ~ 25% failure rate now >> > on most tempest jobs. >> > >> > As can be seen here - >> > >> > https://github.com/openstack/nova/blob/master/nova/virt/libvirt/driver.py#L294-L297 >> > >> > >> > ... the libvirt live_snapshot code is something that our test pipeline >> > has never tested before, because it wasn't a new enough libvirt for us >> > to take that path. >> > >> > Right now it's exploding, a lot - >> > https://bugs.launchpad.net/nova/+bug/1334398 >> > >> > Snapshotting gets used in Tempest to create images for testing, so image >> > setup tests are doing a decent number of snapshots. If I had to take a >> > completely *wild guess*, it's that libvirt can't do 2 live_snapshots at >> > the same time. It's probably something that most people haven't hit. The >> > wild guess is based on other libvirt issues we've hit that other people >> > haven't, and they are basically always a parallel ops triggered problem. >> > >> > My 'stop the bleeding' suggested fix is this - >> > https://review.openstack.org/#/c/102643/ which just effectively disables >> > this code path for now. Then we can get some libvirt experts engaged to >> > help figure out the right long term fix. >> >> Yes, this is a sensible pragmatic workaround for the short term until >> we diagnose the root cause & fix it. >> >> > I think there are a couple: >> > >> > 1) see if newer libvirt fixes this (1.2.5 just came out), and if so >> > mandate at some known working version. This would actually take a bunch >> > of work to be able to test a non packaged libvirt in our pipeline. We'd >> > need volunteers for that. >> > >> > 2) lock snapshot operations in nova-compute, so that we can only do 1 at >> > a time. Hopefully it's just 2 snapshot operations that is the issue, not >> > any other libvirt op during a snapshot, so serializing snapshot ops in >> > n-compute could put the kid gloves on libvirt and make it not break >> > here. This also needs some volunteers as we're going to be playing a >> > game of progressive serialization until we get to a point where it looks >> > like the failures go away. >> > >> > 3) Roll back to precise. I put this idea here for completeness, but I >> > think it's a terrible choice. This is one isolated, previously untested >> > (by us), code path. We can't stay on libvirt 0.9.6 forever, so actually >> > need to fix this for real (be it in nova's use of libvirt, or libvirt >> > itself). >> >> Yep, since we *never* tested this code path in the gate before, rolling >> back to precise would not even really be a fix for the problem. It would >> merely mean we're not testing the code path again, which is really akin >> to sticking our head in the sand. >> >> > But for right now, we should stop the bleeding, so that nova/libvirt >> > isn't blocking everyone else from merging code. >> >> Agreed, we should merge the hack and treat the bug as release blocker >> to be resolve prior to Juno GA. > > > > How can we prevent libvirt issues like this from landing in trunk in the > first place? If we don't figure out a way to prevent this from landing the > first place I fear we will keep repeating this same pattern of failure. > >> >> >> Regards, >> 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 >> :| >> >> _______________________________________________ >> OpenStack-dev mailing list >> OpenStack-dev@lists.openstack.org >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > > > > _______________________________________________ > OpenStack-dev mailing list > OpenStack-dev@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > -- Rackspace Australia _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
