> Go's networking library actually does call epoll/kqueue/etc on the backend, so it is using nonblocking io.

I know, of course. If you reread my comment, you'll notice that it wasn't focusing on the particular syscall that the system uses.

> Using nonblocking IO will provide better performance because it will increase the number of concurrent requests it can serve.

Because of (a), (b), and/or (c), which I addressed in my comment above.