Since 0.2, GNU Artanis has a strong server core for high concurrency. It is named Ragnarok. In the philosophy of the design of GNU Artanis, everything is meant to be flexible and customizable. So the server core is customizable, in case someone thought Ragnarok is not good enough yet.
Ragnarok doesn’t use any popular library for handling events (libev/libuv etc …). It’s a brand new server core based on epoll and delimited continuations.