[tommiegannert]

I was working on adding custom sharding for a reverse proxy in Nginx ten years ago. The code was absolute bare-bones. No comments, no tests. And still it worked really well. Scary and cool, were my thoughts at the time.

There are three things I think stood out (not tied to C10K):

1. The configuration format is light-weight. Compared to Apache, lighttpd and others at the time, you could build a static file server or a reverse proxy in just 3-4 lines of configuration. It lowered the bar of entry, and is probably what led to wide adoption.

2. The core of Nginx was (is?) an async data pipeline. The individual modules (proxy, file system) defined how the pipes tie together, but the actual pumping of data was done in a kernel. You never had to care about epoll(2) and the like; you just defined the DAG. And that was easy to do correctly even in bare-bones C. This was a good architecture.

3. Single-threaded IIRC, which might be the C10K answer you were looking for. Apache had the complicated configuration where you had to decided to use prefork, or threads, or...

Lastly, it was fast. Probably because of (2), and a prerequisite for (3).