Calling async Python code from a spawned tokio task

[ShaneMurphy2]

I'm trying to build some code that runs saved python scripts on demand. As such, the requests are ran in spawned tokio tasks. All of the documentation I could find shows running asynchrounous Python code in the main tokio task in the main function. Here is a minimal example that I tried, but I get behavior that is difficult to understand.

Minimal Example

use pyo3::prelude::*;
use pyo3::{PyResult, Python};

async fn server() -> PyResult<()> {
    let future = Python::with_gil(|py| -> PyResult<_> {
        let asyncio = py.import("asyncio")?;
        pyo3_async_runtimes::tokio::into_future(
            asyncio.call_method1("sleep", (1.into_pyobject(py).unwrap(),))?,
        )
    })?;

    let _ = future.await?;

    Ok(())
}

#[pyo3_async_runtimes::tokio::main]
async fn main() -> PyResult<()> {
    tokio::spawn(server()).await.unwrap()?;

    Ok(())
}

It's essentially the example here just inside tokio::spawn.

Output

<sys>:0: RuntimeWarning: coroutine 'sleep' was never awaited
RuntimeWarning: Enable tracemalloc to get the object allocation traceback
Traceback (most recent call last):
  File "/opt/homebrew/Cellar/[email protected]/3.13.3/Frameworks/Python.framework/Versions/3.13/lib/python3.13/asyncio/base_events.py", line 719, in run_until_complete
    return future.result()
           ~~~~~~~~~~~~~^^
RuntimeError: no running event loop

There is more output, but I think this is the salient error.

Is this expected behavior? I read the section on how asyncio wants the main thread, but does it also need to be initialized per tokio worker thread? Some architectural context would be nice, or a specific design pattern. If there are changes required to support this, I'm happy to give them a shot.

*Updated to be a more minimal example.

[cpu]

In a project with similar requirements I was getting this error until switching to a scope() with the current locals like:

let task_locals = Python::with_gil(pyo3_async_runtimes::tokio::get_current_locals)?;
tokio::spawn(pyo3_async_runtimes::tokio::scope(
    task_locals,
    .....,
));

[ShaneMurphy2]

Hm, I tried something like that, but that only works if the python module and locals are constructed on the main thread. I want something where more like my updated example above.