Hello:
I've discussed this for quite sometime with Dan over IRC and a bit with Zane as well, but basically, Nova thinks that when it gets a reload (aka SIGHUP), nothing else has occurred.
However, oslo.service actually calls stop(), reload() then start() again, which potentially kills all RPC. This has caused a pretty big issue in our gates and it also means that the whole idea behind 'reload nova-compute while upgrading to refresh info' concept is fundamentally broken.
I tried to do some work on this here, however, I wasn't really able to get to the bottom of it. There seems to be a decision that needs to be taken in terms of .. do we change what reload() actually means in oslo_service (it actually is more like a restart, not a reload) or does Nova (and other projects) change their implementation in assuming what reload() does?
https://review.openstack.org/#/c/641907/
This seems to have been floating around for a really long time, so I'd be happy to work with someone to find the fix (and we can totally test it inside OpenStack Ansible by reloading instead of restarting).
Thanks! Mohammed