Comment 3 for bug 1750337

I think that problem is caused by very long time of processing another API call by neutron-server. There is only 1 API worker in neutron-server configured and in logs from example of failed test (above) it looks that just before (few miliseconds) call to show port comes to neutron-server, there was call to show subnet: http://logs.openstack.org/81/545681/1/check/neutron-fullstack/8285bf3/logs/dsvm-fullstack-logs/TestOvsConnectivitySameNetworkOnOvsBridgeControllerStop.test_controller_timeout_does_not_break_connectivity_sigterm_VLANs,openflow-native_/neutron-server--2018-02-18--20-31-43-830810.txt.gz#_2018-02-18_20_34_47_771

and this call was processed for 49(!!!) seconds. In this time neutron-server didn't process any other API call.