epoll has the advantage of operating in O(1) time rather than O(n) time as well which becomes important when you have a lot of file descriptors.
I'd also note that epoll landed with Linux 2.6 so it wasn't really available before 2004. Apache Server was created in 1995 long before epoll and Nginx was initially released in 2004. It's one of those situations where you introduce new capabilities like epoll being able to handle lots of FDs in O(1) time and someone finds a way to use that capability to make something great.
If someone is interested in reading more, "Flash: An Efficient and Portable Web Server" is a good read on the topic: https://www.usenix.org/legacy/events/usenix99/full_papers/pa.... It has no relation to Adobe Flash.
epoll has the advantage of operating in O(1) time rather than O(n) time as well which becomes important when you have a lot of file descriptors.
I'd also note that epoll landed with Linux 2.6 so it wasn't really available before 2004. Apache Server was created in 1995 long before epoll and Nginx was initially released in 2004. It's one of those situations where you introduce new capabilities like epoll being able to handle lots of FDs in O(1) time and someone finds a way to use that capability to make something great.