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Comment by throwawaymaths | Hacker News Reader

Plus sane failure domains: go has had preemptively scheduled green threads from day one but failure domains are really not a thing in go.

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Hm, I think I've read somewhere that both Go and Elixir and kinda cooperative. A process in Elixir can yield control after certain number of reductions (function calls I think) and in Go a goroutine can only yield control on function calls, so if you have an infinite loop just adding numbers it will run uninterrupted. Both of them are "less cooperative" than Python with explicit yield statement. Do I get this right? I started digging into concurrency not that long ago.

Yes technically they are not fully preemptive in the sense that an os thread is (the os sends an interrupt which halts the processing at the CPU level), but in both go and elixir the programmer has no control over when the context switching happens, and "function calls" which are the yield boundaries happen all over the place, so it's "effectively preemptive".

Elixir is in practice more preemptive than go (last I checked with go) because you cannot infinitely loop and lock cpu in elixir -- a loop requires you to tail-call in elixir, so that's a yield boundary, and I'm certain that in earlier go that wasn't the case if you `while true {}`

Yes, unless you're in a BIF or NIF every call is a reduction: https://blog.stenmans.org/theBeamBook/#_reductions so if you call out to native code or are using a VM builtin you can lock it up indefinitely but other than that it's not possible.

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