Function spawn_task 

pub fn spawn_task<F>(
    pending_tasks: &Mutex<Vec<JoinHandle<()>>>,
    description: &'static str,
    fut: F,
)
where
    F: Future<Output = Result<()>> + Send + 'static,

Spawns an async task and tracks its handle in pending_tasks.

Prunes finished handles before adding the new one to prevent unbounded growth.

Panics

Panics if the pending_tasks mutex is poisoned.