Function spawn_blocking 

pub fn spawn_blocking<F, R>(func: F) -> JoinHandle<R> 
where
    F: FnOnce() -> R + Send + 'static,
    R: Send + 'static,

Available on crate feature tasks only.

Spawns a blocking closure on the current tokio runtime, like [tokio::task::spawn_blocking].

The closure is boxed first, so tokio’s blocking task machinery is instantiated once per return type R instead of once per closure type.

Panics

Panics if called outside of a tokio runtime context.