Public bug reported: When a Chassis event happens in the SB database, we attempt to reschedule any possible unhosted gateways [0] *always* due to a problem with the existing logic:
def get_unhosted_gateways(self, port_physnet_dict, chassis_physnets, gw_chassis): unhosted_gateways = [] for lrp in self._tables['Logical_Router_Port'].rows.values(): if not lrp.name.startswith('lrp-'): continue physnet = port_physnet_dict.get(lrp.name[len('lrp-'):]) chassis_list = self._get_logical_router_port_gateway_chassis(lrp) is_max_gw_reached = len(chassis_list) < ovn_const.MAX_GW_CHASSIS for chassis_name, prio in chassis_list: # TODO(azbiswas): Handle the case when a chassis is no # longer valid. This may involve moving conntrack states, # so it needs to discussed in the OVN community first. if is_max_gw_reached or utils.is_gateway_chassis_invalid( chassis_name, gw_chassis, physnet, chassis_physnets): unhosted_gateways.append(lrp.name) return unhosted_gateways 1) is_max_gw_reached is always going to be True (as normally the possible candidates are less than the maximum) 2) unhosted_gateways.append(lrp.name) is executed inside a loop where lrp doesn't change meaning that if there's 3 candidates in the chassis_list, lrp.name is added 3 times to the list!!! 3) Later on, in the caller, we're iterating over the returned list [1] so as it has all the LRPs N times (N being the names of gw chassis), it will do a lot of extra and unnecessary work. This is almost harmless in the sense that it's not breaking any functionality but it creates unnecessary updates on the logical router port: 2020-01-31 15:54:04.669 37 DEBUG ovsdbapp.backend.ovs_idl.transaction [-] Running txn n=1 command(idx=0): UpdateLRouterPortCommand(name=lrp-93b49ece-2dbc-4fcc-84cb-e7afd482a12e, columns={'gateway_chassis': ['0444b1f1-e9a9-4a73-ba78-997c87e61795', '43d98571-ccd6-48ce-bf4f-08f24aeed522', 'fe8f9887-27ef-4724-8cfc-50ec6e3d4a98']}, if_exists=True) do_commit /usr/lib/python3.6/site-packages/ovsdbapp/backend/ovs_idl/transaction.py:84 2020-01-31 15:54:04.670 37 DEBUG ovsdbapp.backend.ovs_idl.transaction [-] Transaction caused no change do_commit /usr/lib/python3.6/site-packages/ovsdbapp/backend/ovs_idl/transaction.py:121 [0] https://github.com/openstack/neutron/blob/4689564fa29915b042547bdeb3dcb44bca54e20c/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/impl_idl_ovn.py#L449 [1] https://github.com/openstack/neutron/blob/858d7f33950a80c73501377a4b2cd36b915d0f40/neutron/services/ovn_l3/plugin.py#L324 ** Affects: neutron Importance: Undecided Assignee: Maciej Jozefczyk (maciej.jozefczyk) Status: Confirmed -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to neutron. https://bugs.launchpad.net/bugs/1861509 Title: [OVN] GW rescheduling logic is broken Status in neutron: Confirmed Bug description: When a Chassis event happens in the SB database, we attempt to reschedule any possible unhosted gateways [0] *always* due to a problem with the existing logic: def get_unhosted_gateways(self, port_physnet_dict, chassis_physnets, gw_chassis): unhosted_gateways = [] for lrp in self._tables['Logical_Router_Port'].rows.values(): if not lrp.name.startswith('lrp-'): continue physnet = port_physnet_dict.get(lrp.name[len('lrp-'):]) chassis_list = self._get_logical_router_port_gateway_chassis(lrp) is_max_gw_reached = len(chassis_list) < ovn_const.MAX_GW_CHASSIS for chassis_name, prio in chassis_list: # TODO(azbiswas): Handle the case when a chassis is no # longer valid. This may involve moving conntrack states, # so it needs to discussed in the OVN community first. if is_max_gw_reached or utils.is_gateway_chassis_invalid( chassis_name, gw_chassis, physnet, chassis_physnets): unhosted_gateways.append(lrp.name) return unhosted_gateways 1) is_max_gw_reached is always going to be True (as normally the possible candidates are less than the maximum) 2) unhosted_gateways.append(lrp.name) is executed inside a loop where lrp doesn't change meaning that if there's 3 candidates in the chassis_list, lrp.name is added 3 times to the list!!! 3) Later on, in the caller, we're iterating over the returned list [1] so as it has all the LRPs N times (N being the names of gw chassis), it will do a lot of extra and unnecessary work. This is almost harmless in the sense that it's not breaking any functionality but it creates unnecessary updates on the logical router port: 2020-01-31 15:54:04.669 37 DEBUG ovsdbapp.backend.ovs_idl.transaction [-] Running txn n=1 command(idx=0): UpdateLRouterPortCommand(name=lrp-93b49ece-2dbc-4fcc-84cb-e7afd482a12e, columns={'gateway_chassis': ['0444b1f1-e9a9-4a73-ba78-997c87e61795', '43d98571-ccd6-48ce-bf4f-08f24aeed522', 'fe8f9887-27ef-4724-8cfc-50ec6e3d4a98']}, if_exists=True) do_commit /usr/lib/python3.6/site-packages/ovsdbapp/backend/ovs_idl/transaction.py:84 2020-01-31 15:54:04.670 37 DEBUG ovsdbapp.backend.ovs_idl.transaction [-] Transaction caused no change do_commit /usr/lib/python3.6/site-packages/ovsdbapp/backend/ovs_idl/transaction.py:121 [0] https://github.com/openstack/neutron/blob/4689564fa29915b042547bdeb3dcb44bca54e20c/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/impl_idl_ovn.py#L449 [1] https://github.com/openstack/neutron/blob/858d7f33950a80c73501377a4b2cd36b915d0f40/neutron/services/ovn_l3/plugin.py#L324 To manage notifications about this bug go to: https://bugs.launchpad.net/neutron/+bug/1861509/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : yahoo-eng-team@lists.launchpad.net Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp