Comment by fsmunoz

An update: I've spent some time taking a much deeper look, and while I can't guarantee it's perfect, I added a different approach for Clack+Woo, documented here: https://github.com/fsmunoz/datastar-cl/blob/main/SSE-AND-WOO...

In short: I've replace the Common Lisp loop (that works for Hunchentoot since it opens threads, but doesn't for Woo since it blocks) with a deeper integration into the event loop:

> And that was the main change: looking at the innards of it, there are some features available, like woo.ev:evloop. This was not enough, and access to the libev timer was also needed. After some work with lev and CFFI, the SDK now implements a Node.js-style approach using libev timers via woo.ev:evloop and the lev CFFI bindings (check woo-async.lisp).

This is likely (almost surely) not perfect or even ideal, but it does seem to work, and I've been testing the demo app with 1 worker and multiple clients.