Why does tokio::runtime::Handle::spawn appear to not run here?

It will work if I start main in a tokio runtime context with #[tokio::main] but I would like to adapt this code to be able to work in and outside of a runtime. If inside a runtime, it should use that existing runtime, if outside, it should create a runtime for itself to use.

fn runtime() -> (tokio::runtime::Handle, Option<tokio::runtime::Runtime>) {
    if let Ok(handle) = tokio::runtime::Handle::try_current() {
        (handle.clone(), None)
    } else {
        let runtime = tokio::runtime::Builder::new_multi_thread()
        (runtime.handle().clone(), Some(runtime))

async fn another_async() -> anyhow::Result<()>{
    println!("hello again!");

async fn hello_async() -> anyhow::Result<()>{
    for _ in 0..10 {

fn run_spawn() -> (tokio::runtime::Handle, Option<tokio::task::JoinHandle<anyhow::Result<()>>>) {
    let (runtime_handle, _runtime) = runtime();
    let join_handle = runtime_handle.spawn(hello_async());
    (runtime_handle.clone(), Some(join_handle))

fn main(){
   loop {}


A Handle does not keep the runtime alive - only the singly-owned Runtime type does. So you probably want to return an Option<Runtime> from that function.

1 Like

Thank you that fixed it. _runtime was being dropped at the end of run_spawn and aborting, I needed to return it to the main function or use std::mem::forget to prevent it from being dropped.

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