As Kevin pointed out and as I also can see from code [1] (both for methods _add_auto_ip and _add_ip_from_pool) the action of associating a floating ip to server is a two step process that involve creating an unassociated FIP which then gets assigned to a fixed ip via its port uuid (neutron case). It seems that the race part is where two separate threads get hold of the same FIP uuid: that can happen into cases (as far as I can see): a) pull a FIP from a list of available ones; b) create a fresh one.
I wonder if the source of contention is in the a) code path, and whether there's a chance to protect this critical region on client-side. Two separate client requests should lead to two separate FIPs being generated and thus lead to separate associations and thus no contention. [1] https://github.com/openstack-infra/shade/blob/d026cab5c7548517aa15e969fdd336b9fc663e7d/shade/openstackcloud.py#L3955 [2] https://github.com/openstack-infra/shade/blob/d026cab5c7548517aa15e969fdd336b9fc663e7d/shade/openstackcloud.py#L3296 [3] https://github.com/openstack-infra/shade/blob/d026cab5c7548517aa15e969fdd336b9fc663e7d/shade/openstackcloud.py#L3304 ** No longer affects: nova -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to neutron. https://bugs.launchpad.net/bugs/1581220 Title: race leads same floating ip to be associated to separate ports Status in neutron: Incomplete Bug description: It looks like steps to create server as outlined in [2] lead to the same FIP being associated to two individual ports [1] (offending fip f1169479-7d88-4526-a60a-82f18b617077). It looks like two interleaving calls to do FIP association by port-id will end up clashing. This has been reproduced in Kilo, but we would need to find out if the race is still possible in newer versions. [1] https://gist.github.com/cloudnull/d90eff7efc524844d8d3504fea8fa419 [2] https://gist.github.com/cloudnull/2f3931e51062dc7b325faf9a24974006 To manage notifications about this bug go to: https://bugs.launchpad.net/neutron/+bug/1581220/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : [email protected] Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
