> - The VM JITs, but inserts a preamble before every function call saying “Before executing this function, should I switch to another green thread first?”, and

> - The VM JITs, but inserts a preamble before every function call saying “Before executing this function, should I switch to another green thread first?”, and thus, so long as you call functions frequently enough, you “preempt” yourself. This is how Go does it, and it’s a well known thing in Go that if you never call a function for a while (like just doing a really huge for loop), the current goroutine doesn’t yield execution and hogs the whole OS thread. I'm not sure of the implementation details, but this hasn't been true for a while in Go. As of Go 1.14, goroutines are asynchronously preemptible, so loops without function calls no longer deadlock the scheduler or GC: https://go.dev/doc/go1.14#runtime https://go.dev/doc/go1.14#runtime