[gnufied]

Author of Packet (https://github.com/gnufied/packet) a Reactor library that did use Ruby IO primitives here. I wrote this before, eventmachine had pure Ruby reactor. Non blocking calls were introduced in Ruby 1.8.5 IIRC and my library made heavy use of them, and they were buggy. Some issues I found:

* select() call used to segfault. * the non blocking read/write behaved very differently under different OSes and I am not talking Windows. There were differences between Linux and OSX for example. * Again frequent crashes when reading/writing when nonblock flag is set.

I am sure, situation is lot better now but for building a reactor library, native Ruby IO primitives fell short. There is always lack of advanced selectors (Epoll/KQueue) as well.

Now as I replied to thomas(?) below and since you yourself have wrapped libevent for Ruby 1.9, there were severe limitation in interpreter back then for even libevent wrapper to work. So I guess, given historical reasons, it made sense Eventmachine did not use native Ruby IO primitives or libevent.