when to .await JoinHandle type generated by tokio::spawn

[LIPUU]

If I comment out those three lines of code, the program exits early and does not print out the full result. What I'm asking is, is there a best practice for when I should .await the JoinHandle type generated by tokio::spawn ? thank you!

#[tokio::main]
async fn main() {

    let mut handles = Vec::with_capacity(10);
    for i in 0..10 {
        handles.push(tokio::spawn(my_bg_task(i)));
    }
    

// 🔺🔺🔺
    for handle in handles {
        handle.await.unwrap();
    }
// 🔺🔺🔺


}

async fn my_bg_task(i: u64) {
    println!("{}",i)
}

[Darksonn]

When you return from main, the runtime will start shutting down, which includes killing all other spawned tasks. You should await tasks when you need to wait for them to finish.

[LIPUU]

thank you

[LIPUU]

I have some new understanding of this problem. This actually involves the shutdown of runtime. What happens when a runtime is dropped can be found at this link.
So what will be closed? Unblocked worker thread. And what will be waiting to be completed?
blocking thread（generated by spawn_blocking） and worker threads that are already blocked by some synchronization code（for example ,the code has std::thread::sleep).
But in my sample code for this problem, my_bg_task function doesn't have any code that makes the runtime wait for finish. when main finishes executing,runtime is dropped and all the unexecuted tasks are discarded.

[Darksonn]

Yes. Generally the solution is to prevent the runtime from starting shutdown until your tasks have completed.