Looking slight further back in the logs before the virNWFilterUndefine API call, I see an attempt to start a guest:
2014-01-21 04:15:07.124+0000: 29622: debug : virDomainCreateWithFlags:9482 : dom=0x7f31a0001900, (VM: name=instance-00000053, uuid=9199131f-7ae8-4e9e-9065-0b47787180c1), flags=0
the logs show that this never completes. This pretty much confirms that we're hitting that libvirt race condition between parallel domain start / nwfilter changes.
Looking slight further back in the logs before the virNWFilterUndefine API call, I see an attempt to start a guest:
2014-01-21 04:15:07.124+0000: 29622: debug : virDomainCreate WithFlags: 9482 : dom=0x7f31a0001900, (VM: name=instance- 00000053, uuid=9199131f- 7ae8-4e9e- 9065-0b47787180 c1), flags=0
the logs show that this never completes. This pretty much confirms that we're hitting that libvirt race condition between parallel domain start / nwfilter changes.