When you want to do long-running blocking work (either computation, or synchronous IO from some library that doesn't use futures), you usually want to farm that

When you want to do long-running blocking work (either computation, or synchronous IO from some library that doesn't use futures), you usually want to farm that work out to a thread pool. I think Tokio provides convenience functions for doing that. It's also possible to write a long-running computation as a future, which can yield after some smaller amount of work to let some IO get done. But I'm not sure if that's the recommended approach.