Function spawn_blocking

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

spawn_blocking is used for executing a task(without async) with heavy computation or blocking io.

To used it, users may initialize a thread pool and attach it on creating runtime. Users can also set BlockingStrategy for a runtime when there is no thread pool. WARNING: DO NOT USE THIS FOR ASYNC TASK! Async tasks will not be executed but only built the future!