This is caused by the restart of the ovs daemons (part of the upgrade process - its done post install to minimize downtime):
2015-05-28 14:24:18.336 47866 ERROR neutron.agent.linux.ovsdb_monitor [-] Error received from ovsdb monitor: ovsdb-client: unix:/var/run/openvswitch/db.sock: receive failed (End of file)
I would suspect that the code in neutron is not behaving very nicely in terms of recovering from this disconnect, resulting the in the lockup you see.
This is caused by the restart of the ovs daemons (part of the upgrade process - its done post install to minimize downtime):
2015-05-28 14:24:18.336 47866 ERROR neutron. agent.linux. ovsdb_monitor [-] Error received from ovsdb monitor: ovsdb-client: unix:/var/ run/openvswitch /db.sock: receive failed (End of file)
I would suspect that the code in neutron is not behaving very nicely in terms of recovering from this disconnect, resulting the in the lockup you see.