Notify: basic example intermittently fails

[davidcopp]

When running the given Notify - basic example (tokio 1.13.0 on MacOs 11.6), the correct output is

sending notification
received notification

but more often I get only

sending notification

Joining the spawned task fixes the problem:

    let join = tokio::spawn(async move {
        notify2.notified().await;
        println!("received notification");
    });

    println!("sending notification");
    notify.notify_one();
    println!("joining spawned task");
    join.await.expect("spawn failed");
    println!("spawned task completed");

Could be a doc or a real bug, not sure.

[Darksonn]

Thanks for reporting. This is a problem in the documentation - the spawned task is killed when main returns, so it may never get to run.