alt Hacker News> the thread sleeps until ready and the kernel abstracts it away.
Sure, but once you involve the kernel and OS scheduler things get 3 to 4 orders of magnitude slower than what they should be.
The last time I was working on our coroutine/scheduling code creating and joining a thread that exited instantly was ~200us, and creating one of our green threads, scheduling it and waiting for it was ~400ns.
You don't need to wait 10 years for someone else to design yet another absurdly complex async framework, you can roll your own green threads/stackful coroutines in any systems language with 20 lines of ASM.
1. Why can’t we have better green threads implementations with better scheduling models?
2. Unchecked array operations are a lot faster. Manual memory management is a lot faster. Shared memory is a lot faster.
Usually when you see someone reach for sharp and less expressive tools it’s justified by a hot code path. But here we jump immediately to the perf hack?
3. How many simultaneous async operations does your program have?