openstack/nova
Code Issues Proposed changes

Don't wait for vif plug events during _hard_reboot

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Originally, in change Id188d48609f3d22d14e16c7f6114291d547a8986 we
added a re-initialization of volumes, encryptors, and vifs to hard
reboot. When creating the libvirt domain and network, we were waiting
for vif plug events from neutron when we replugged the vifs. Then, we
started seeing timeouts in the linuxbridge gate job because compute
was timing out waiting for plug events from neutron during a hard
reboot.

It turns out that the behavior of neutron plug events depends on what
vif type we're using and we're also using a stale network info_cache
throughout the hard reboot code path, so we can't be 100% sure we know
which vifs to wait for plug events from anyway. We coincidentally get
some info_cache refreshes from network-changed events from neutron,
but we shouldn't rely on that.

Ideally, we could do something like wait for an unplug event after we
unplug the vif, then refresh the network_info cache, then wait for the
plug event. BUT, in the case of the os-vif linuxbridge unplug method,
it is a no-op, so I don't think we could expect to get an unplug
event for it (and we don't see any network-vif-unplugged events sent
in the q-svc log for the linuxbridge job during a hard reboot).

Closes-Bug: #1744361

Change-Id: Ib0cf5d55750f13d0499a570f14024dca551ed4d4
This commit is contained in:
melanie witt 2018-02-01 22:27:57 +00:00
parent d189e68227
commit 236bb54493
2 changed files with 8 additions and 2 deletions
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2
nova/tests/unit/virt/libvirt/test_driver.py
View File

@ -12608,7 +12608,7 @@ class LibvirtConnTestCase(test.NoDBTestCase,
block_device_info=block_device_info, mdevs=[uuids.mdev1])
mock_create_domain_and_network.assert_called_once_with(self.context,
dummyxml, instance, network_info,
block_device_info=block_device_info)
block_device_info=block_device_info, vifs_already_plugged=True)
@mock.patch('oslo_utils.fileutils.ensure_tree')
@mock.patch('oslo_service.loopingcall.FixedIntervalLoopingCall')

8
nova/virt/libvirt/driver.py
View File

@ -2708,8 +2708,14 @@ class LibvirtDriver(driver.ComputeDriver):
# Initialize all the necessary networking, block devices and
# start the instance.
# NOTE(melwitt): Pass vifs_already_plugged=True here even though we've
# unplugged vifs earlier. The behavior of neutron plug events depends
# on which vif type we're using and we are working with a stale network
# info cache here, so won't rely on waiting for neutron plug events.
# vifs_already_plugged=True means "do not wait for neutron plug events"
self._create_domain_and_network(context, xml, instance, network_info,
block_device_info=block_device_info)
block_device_info=block_device_info,
vifs_already_plugged=True)
self._prepare_pci_devices_for_use(
pci_manager.get_instance_pci_devs(instance, 'all'))