You know how the first time you learned about tcp sockets you made a server that spawned a new thread to handle an incoming connection (or maybe not, people learn differently nowadays).
With the fibers implementation you can just do that. It doesn't kill your performance, and you don't need to go to a painful async model just for performance reasons.
Pretty much. You get to pretend inside your fibers that you're actually running threads. IIRC (it's been a while) you also get proper stack trace when something barfs, the importance of which cannot be overstated.
What are they though? Is this a library for an existing language? A runtime scheduler like the one that does goroutines in Go? If it were open sourced, how would I use it?
It’s just a library that allows easier development of C++ servers in the synchronous, thread-per-requests style, similar to working in Go but a bajillion times better because it’s not in Go.
With the fibers implementation you can just do that. It doesn't kill your performance, and you don't need to go to a painful async model just for performance reasons.