> Nginx performance without stats collections is on part with Envoy, but our Lua stats collection slowed Nginx on the high-RPS test by a factor of 3. This was expected given our reliance on lua_shared_dict, which is synchronized across workers with a mutex.
The `a factor of 3` is quite large to me. Maybe you put all your stats in lua_shared_dict? You don't need to synchronize the stats every time. Since the collection regularly happens in per-minute frequency, you can put the stats as Lua table, and synchronize them once per 5/10 seconds.
It look like that the compared Nginx is configured with a system which has been survived for years and not up-to-date. The company I worked with used a single virtual server to hold all traffic and routed them with Lua code dynamically. And the upstream is chosen by Lua code too. There is no need to reload Nginx when a new route/upstream is added. We even implemented 'Access Log Service' like feature so that each user can have her favorite access log (by modifying the Nginx core, of course).
However, I don't think this post is incorrect. What Envoy surpasses Nginx is that it has a more thriving developer community. There are more features added into Envoy than Nginx in the recent years. Not only that, opening discussion of Nginx development is rare.
Nginx is an old, slow giant.