This sounds very similar to priority inversion. E.g. if you have Thread T_high running at high priority and thread T_low running at low priority, and T_low holds a lock that T_high wants to acquire, T_high won't get to run until T_low gets scheduled.
The OS can detect this and make T_low "inherit" the priority of T_high. I wonder if there is a similar idea possible with tokio? E.g. if you are awaiting a Mutex held by a future that "can't run", then poll that future instead. I would guess detecting the "can't run" case would require quite a bit of overhead, but maybe it can be done.
I think an especially difficult factor is that you don't even need to use a direct await.
let future1 = do_async_thing("op1", lock.clone()).boxed();
tokio::select! {
_ = &mut future1 => {
println!("do_stuff: arm1 future finished");
}
_ = sleep(Duration::from_millis(500)) => {
// No .await, but both will futurelock on future1.
tokio::select! {
_ = do_async_thing("op2", lock.clone()) => {},
_ = do_async_thing("op3", lock.clone()) => {},
};
}
};
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