`timeout` doesn't work as expected

[kanarus]

I created a demo project: https://github.com/kanarus/test-compio-timeout. The core part of this is:

    for _ in 0..100 {
        let x = timeout!(
            std::time::Duration::from_secs(2),
            heavy_task(std::time::Duration::from_secs(3))
        ).await;
        
        let y = my_timeout(
            sleep!(std::time::Duration::from_secs(2)),
            heavy_task(std::time::Duration::from_secs(3))
        ).await;
        
        println!("{x:?}, {y:?}");
    }

This demo provides compio and monoio feature flag to easily switch runtimes, and

• my_timeout is a custom, generic timeout implementation.
• sleep! calls {compio or monoio}::time::sleep(~).await based on selected feature.
• timeout! calls {compio or monoio}::time::timeout(~).await.ok() based on selected feature.

My environment

uname -a
Linux ThinkPad 6.8.0-79-generic #79~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Fri Aug 15 16:54:53 UTC 2 x86_64 x86_64 x86_64 GNU/Linux

Expected behavior (by cargo run --features monoio)

• print None, None every 4 seconds ( 2 secs + 2 secs ).

None, None
None, None
None, None
None, None
None, None
None, None
None, None
None, None
None, None
None, None

compio behavior (by cargo run --features compio)

• print lines in irregular interval.
• printed content is flaky.
• is cancellation or something buggy?

None, Some("done")
Some("done"), Some("done")
Some("done"), None
Some("done"), Some("done")
None, None
None, Some("done")
None, None
Some("done"), Some("done")
Some("done"), Some("done")
Some("done"), Some("done")

[George-Miao]

@kanarus Can reproduce. This is definitely weird. Thanks for the issue.