coroutine and async in tokio

test.rs

tokio::runtime::Builder::new_multi_thread().worker_threads(4).enable_all().build().unwrap().block_on(
    async{
        let mut handles = Vec::with_capacity(8);

        for i in 1..4{
            let joinhandle = tokio::spawn(async move{
                tokio::task::yield_now().await;
                co_run(i).await;
            });
            handles.push(joinhandle);
            // joinhandle.await; // sequence
        }
        futures::future::join_all(handles).await;
    }
);

}
  
async fn co_run(id : i32){
    println!("begin {}",id);
    // simulate io time wait
    let result = co_sleep(1).await; 
    println!("end {}:{}",id,result);
}

async fn co_sleep(num : i32) -> i32{
    std::thread::sleep(std::time::Duration::from_secs(1));
    num+1
}