Ah, I understand now. I misinterpreted "no thread overhead" as meaning "I'm not running things in multiple threads", like the current node.js/javascript obsession, where we just run code in one thread and use a bunch of async to "parallelise". Sorry!
I've (badly) written code like you describe -- usually by abusing fork to do my initial data structure setup, then using C pipes to pass jobs around. I suspect there are much better ways of doing it, but that parallelised well enough for the stuff I was doing. I'd be interested to know if there are good libraries (or best practices) for doing this kind of parallelism.
I was also confused. I agree that touching raw threads is usually not the right thing to do, and chains of parallel coroutines are one of the good abstractions. It’s crazy how few languages have easy access to that very basic abstraction.
I've (badly) written code like you describe -- usually by abusing fork to do my initial data structure setup, then using C pipes to pass jobs around. I suspect there are much better ways of doing it, but that parallelised well enough for the stuff I was doing. I'd be interested to know if there are good libraries (or best practices) for doing this kind of parallelism.