There is a difference between blocking and non-blocking, which is what I am asking about. Language runtimes apparently cannot provide non-blocking DNS (as evidenced by this article, and the other one I linked which was on HN a week or so ago).

DNS seems like it perfectly fits the model of "give me a buffer (to hold the resolved IP), and I will wake you up when it's filled". Maybe io_uring (/ IOCP?) already can support this, and these articles are just mistaken about the current (or soon-to-be) state-of-the-art? Or is there some fundamental reason about DNS that make writing a non-blocking resolver very very difficult?

It's just very odd to me that userspace apps are creating their own blocking thread pools just to run DNS stuff, when they can do seemingly everything else with just a single thread if they wanted to.

(edited a few times, sorry if I caught someone who was mid-reply)