Comment 4 for bug 1930406

+1 what Sean said. We have had a known issue documented since Stein indicating that threads=1 has to be used otherwise it will be possible for oslo.messaging to attempt a reply on a different eventlet thread than the request came from and cause timeouts.

Unfortunately I'm not aware of anything we can do here other than increase the number of processes.

This might be yet another reason we will want to enable nova to run with regular threads -- then we wouldn't have to run oslo.messaging rpc with the eventlet executor and theoretically could run wsgi with threads > 1.