Earlier quoted context omitted.
As I recall it, goroutines are in fact cooperative with implicit yield points. The implicit behavior is what I believe go means by “for all intents and purposes” Particularly, I believe all function calls are implicitly yield, which means you can usually pretend that its preemptive through normal coding practices; but you can still never yield through a while(1){} (i think there was a proposal to add implicit yield o…
The implicit yield points you're talking about is sleep or wait ( noop in other terms). It's also not exactly a yield, it calls the scheduler to tell it to schedule (meaning the scheduler could decide to run again the exact same goroutine that noop-ed). Finally, goroutines are not just cooperative, they also run in parallel in a pool of threads.
Isn’t sleep() usually defined as not giving up control? It’s semantically a busyspin for n seconds. That is, it’s explicitly not a yield point; it's a blocking call, and it doesn’t give control back to scheduler.
And isn't wait() usually defined as, semantically, a non-blocking spinloop with a condition (hence notify() or poll())?
Which makes sleep(), wait(), yield() and noops very different.
I suppose in go, if yield() is implicit on any function call, then sleep() will immediately call yield() before actually sleeping (but once started, it’ll hold control until finished)
I'm pretty sure the implicit yield points are actually yield(), though I haven't verified; it's the only one of the sleep/wait/yield semantics that would be sensible to be implicit as far as I can tell.
>It's also not exactly a yield, it calls the scheduler to tell it to schedule
As far as I was aware, thats exactly what yield means; it yields execution control back to the scheduler. I suppose in eg, a generator, it yields control back to the caller, but afaik thats fundamentally the same meaning (the caller is the scheduler). Can you expand?
>Finally, goroutines are not just cooperative, they also run in parallel in a pool of threads.
Sure, but is that relevant? I assume async.core also trivially supports thread pooling, and is presumably equivalent to go’s pool. The only real difference is go implicitly instiates the pool, while core.async presumably makes it an explicit function to call