alt Hacker NewsThat's because they are very rarely useful. This was true then and it's still true now. There's just not many workloads where it makes sense to need to rapidly launch a thread that doesn't need to do much of anything but does need to exist for a while before terminating.
What is useful is the state machine aspects of things like coroutines or async/await, but those aren't quite fibers and very much aren't M:N threading. A major use of them is in UI where they have strict thread requirements even.
Exactly. When I started getting into go 15 years ago, and 10 years ago or so into elixir, I loved the easy concurrency and tried to use it to the maximum possible. What I discovered is that they're just aren't that many things that you can do concurrently. Reading many different files or servicing many different network sockets being the exception, but realistically that isn't done very often relative to single threaded stuff.
State machine/management is really what is most useful