Comment 0 for bug 1026029

I was running into a exception when trying to reboot(automatically) all vm instances after the compute node failover(nova version is Diablo);

this code piece maybe related:
nova/virt/libvirt/connection.py:501
    virt_dom = self._conn.lookupByName(instance['name'])

on the newly up host, there is no virt Domain, the above lookupByName would definitely failed and throw a exception;
to put this calling in a `try exception' may be better.

detailed trace:

2012-07-18 15:55:09,422 CRITICAL nova [-] Domain not found: no domain with matching name 'instance-0000007a'
(nova): TRACE: Traceback (most recent call last):
(nova): TRACE: File "/usr/bin/nova-compute", line 49, in <module>
(nova): TRACE: service.wait()
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/nova/service.py", line 357, in wait
(nova): TRACE: _launcher.wait()
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/nova/service.py", line 107, in wait
(nova): TRACE: service.wait()
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/eventlet/greenthread.py", line 166, in wait
(nova): TRACE: return self._exit_event.wait()
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/eventlet/event.py", line 116, in wait
(nova): TRACE: return hubs.get_hub().switch()
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/eventlet/hubs/hub.py", line 177, in switch
(nova): TRACE: return self.greenlet.switch()
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/eventlet/greenthread.py", line 192, in main
(nova): TRACE: result = function(*args, **kwargs)
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/nova/service.py", line 77, in run_server
(nova): TRACE: server.start()
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/nova/service.py", line 137, in start
(nova): TRACE: self.manager.init_host()
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 176, in init_host
(nova): TRACE: self.reboot_instance(context, instance['id'])
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/nova/exception.py", line 100, in wrapped
(nova): TRACE: return f(*args, **kw)
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 118, in decorated_function
(nova): TRACE: function(self, context, instance_id, *args, **kwargs)
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 636, in reboot_instance
(nova): TRACE: self.driver.reboot(instance_ref, network_info)
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/nova/exception.py", line 100, in wrapped
(nova): TRACE: return f(*args, **kw)
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/connection.py", line 501, in reboot
(nova): TRACE: virt_dom = self._conn.lookupByName(instance['name'])
(nova): TRACE: File "/usr/lib/python2.7/dist-packages/libvirt.py", line 1870, in lookupByName
(nova): TRACE: if ret is None:raise libvirtError('virDomainLookupByName() failed', conn=self)
(nova): TRACE: libvirtError: Domain not found: no domain with matching name 'instance-0000007a'