In every user-mode thread
or stackless coroutine (async/await) implementation I know, the construct is pinned (i.e. can't be preempted) while there's a foreign frame on the stack. There is no advantage to either design on that front.
But 1. there's no speed penalty in Java for doing that, and 2. In Java, calling native functions that block (which is the only time this limitation matters) is rare, especially in high concurrency situations where you'd use virtual threads in the first place.
