Yeah Crossbeam is awesome. And the pre-1.0 story about a similar interface that existed in std, until it was found to be unsound, is totally fascinating: https:

Yeah Crossbeam is awesome. And the pre-1.0 story about a similar interface that existed in std, until it was found to be unsound, is totally fascinating: https://github.com/rust-lang/rust/issues/24292 https://github.com/rust-lang/rust/issues/24292. (Prior to that, std::mem::forget was marked unsafe!) Another detail that's worth clarifying for folks reading along: The API in this example will automatically join all threads at the end of the crossbeam::scope. (That is indeed what makes it safe.) So if your goal is to fire off a background thread that will outlive the current function, you usually need to go back to std::thread::spawn and live with its 'static requirement.