Why?
I ask because I wrote a port scanner professionally once, and I got away with using one fd for network I/O. I can only think of one case where you end up using a lot of fds and that is if you're using TCP sockets and connect(2) where you'd end up with one fd/tested port, and that's not good.
After recompiling with Go 1.4 (from Go 1.2 - apparently the network poller was rewritten?) I'd start running out of file descriptors really fast, all leaking deep in net/http.ReadRequest.
Turns out http.DefaultServer doesn't have any default ReadTimeout, so when a client goes away before finishing a request I'd lose the goroutine and the file descriptor with it.
So yeah, you probably also want to explicitly set http.Server.ReadTimeout if you are not doing weird streaming/"comet" stuff.
I wrote about handling this in Python: http://www.mobify.com/blog/http-requests-are-hard/
