Comment 2 for bug 1663458

The problem here is that the backoff RPC client raises tunnel_sync timeout up to 480 secs, and the agent does not respond to SIGTERM immediately, but only after tunnel_sync running at the moment exits; so systemd decides (after 90 secs of waiting) to kill the agent with SIGKILL, which makes ryu green thread to stay unkilled. The problem is that the default systemd wait time for SIGTERM processing (90s) is a lot shorter than the max time to wait for RPC reply (TRANSPORT.conf.rpc_response_timeout * 10). It's either we raise systemd wait time to that level, or we change the max ceiling for backoff. Probably the former, which would mean Won't Fix for neutron, and a change in RDO, but I need to think about it a bit more.