Socket - handling large numbers of incoming connections

[Stefan via Digitalmars-d-learn]

How about https://github.com/dcarp/asynchronous ? Asyncio Socket 
handling is sometimes quite nice. It's performance is okay for 
nearly no effort and the code looks clean.
Details here: 
http://dcarp.github.io/asynchronous/asynchronous/streams/startServer.html

vibe.d also offers a fiber based asyncio way of dealing with 
sockets.
http://vibed.org/docs#tcp-server

Maybe it fits your needs.