[flaghacker]

Tokio is using the Rust async features, which are not green threads. In the former code has to explicitly mark potential yield points, in the latter green threads can be scheduled by the runtime without any help from the code itself.

As a historical note, Rust used to have green threads but they were abandoned a long time ago. This is a good talk about both the differences between different forms of concurrency/async and Rusts history with them: https://www.infoq.com/presentations/rust-2019/ (includes a transcript)