Very interesting read! But I want to point out a small correction - the DNS collapse issue at HAProxy, along with O(N^2), also had some O(N^3) code paths, which is just mind-blowing.
> Production Lesson: Code that "works fine" at small scale may still hide O(N²) or worse behavior. At hundreds or thousands of nodes, those costs stop being theoretical and start breaking production.
Also, I believe this should be the correct GitHub issue link - https://github.com/haproxy/haproxy/issues/1404
> Production Lesson: Code that "works fine" at small scale may still hide O(N²) or worse behavior. At hundreds or thousands of nodes, those costs stop being theoretical and start breaking production.