On Tue, Aug 08, 2017 at 09:32:03PM -0400, Russell Bryant wrote: > On Tue, Aug 8, 2017 at 8:04 PM, Ben Pfaff <[email protected]> wrote: > > On Mon, Jul 31, 2017 at 04:53:03PM -0400, Russell Bryant wrote: > >> I wanted to share the idea before I code it to see if it makes sense. > >> I imagine the patch would be small, though. > >> > >> We currently provide HA for ovn-northd by using Pacemaker to ensure > >> that ovn-northd is running only one time somewhere in a cluster. > >> > >> What if we made ovn-northd acquire an OVSDB lock on the southbound > >> database before it did any real work? That way we could start > >> multiple copies of ovn-northd in a cluster, but only one would be > >> active at a time. > > > > I think it's a reasonable approach. > > > > It means that we'll have to make sure that clustered OVSDB, when it > > becomes available, supports locks. I hadn't yet decided whether locks > > were important for that use case. It sounds like they might be. > > Maybe, unless further iteration of ovn-northd to have more than one > able to perform work at the same time is done in a way that drops the > lock usage. > > However, we make use of OVSDB locks from the OpenStack OVN integration, as > well. > > That use case is: > > There are several clients of the OVN Northbound database, all running > their own IDL instance. This is multiple threads of a neutron-server > process that's running on multiple hosts. We need a single worker > across all hosts to handle state changes to the "up" column of > Logical_Switch_Port. We have a single thread in each neutron-server > that attempts to acquire a lock for this. Whichever one currently > holds the lock handles the "up" state changes and associated OpenStack > notifications.
OK, I did not know about that. Thanks for the information. _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
