CloudFlare generates 50gb/s of logs globally and have handled collecting this volume in two ways. Historically the logs are sent to a local syslog-ng through the use of a PIPE and the forwarded to central logger. This can be done with nginx with no patches by just treating the PIPE as file. Just make sure you do a little buffering inside nginx.

access_log /dev/nginx_access log_format_name buffer=64k flush=10s;

Since this is a pipe there is still some blocking IO, but no worse off then writing to local file.

The way we are migrating will be non-blocking IO through the use of Lua Resty log module ( https://github.com/cloudflare/lua-resty-logger-socket ).

We will write up a blog post at some point but hopefully this is useful to you. In the future we are going to be going one step further and have NGINX emit protobuff files. Feel free to email dane AT cloudflare.com if you have any questions.