HA router state change takes too much time to notify neutron server.
It takes almost 16s, by default ha_vrrp_advert_int 2s, for a single
HA router state change.
In this 16s time, assuming that a HA router meets 8 times HA router
state change. After this 16s, the first change dequeue and notify the
neutron server, then the 2nd, 3rd, and so on. Things are now becoming
interesting, after this 16 seconds if you run
`neutron l3-agent-list-hosting-router ha_router_id`, you may see the
router state in one specific agent is alternatively changing in active
and standby. It's not stay in the real state, because of the delay
notification.
This patch sets the BatchNotifier interval to ha_vrrp_advert_int (default
2s) to make the HA router state change notification more faster.
NOTE: the BatchNotifier event queue is needed, because the HA router state
change needs to be sent in a proper order. Then the neutron server could set
the HA state properly.
Closes-Bug: #1612069
Change-Id: Ife687038d31bd1e1ee264ff8b6ae1264fdd05489
e795a3fcf8