Spurious wakeups with timerfd + Interval about async-timer HOT 8 CLOSED

yeah I'll check what PollEvented does, but there is definitely no read notification and yet tokio calls in the future.
So probably PollEvented registers more than read interest with mio

from async-timer.

I can confirm that tokio-rs/tokio#2221 indeed fixed this issue!

from async-timer.

Ok, so I know that tokio tends to do some spurious polls, but it should not be so often...
After wake up, you restart timer by updating to new timestamp and poll it...
Obviously mio would return that it is not ready, otherwise we would clear ready flag https://github.com/DoumanAsh/async-timer/blob/master/src/oneshot/timer_fd.rs#L165

Logically speaking I think I did everything I could, but in case of kevent and timerfd timers I depend on tokio to wake timer.
POSIX timer is using my own waker to wake once (by calling callback from signal)

Out of curiosity could you try the same with single threaded runtime?
I'll try to check tokio integration myself once I'll have time

P.s. interesting thing to point out is that I clear readiness only on read event, I wonder if it wakes up with non-read events? 😄

from async-timer.

Note to self: checked macOS, has the same problem.
Type of scheduler doesn't matter

Added prints to see when it is called:

SystemTime { tv_sec: 1579776488, tv_nsec: 546224000 } poll_next
timer not ready
SystemTime { tv_sec: 1579776488, tv_nsec: 546280000 } poll_next
timer not ready
SystemTime { tv_sec: 1579776488, tv_nsec: 546322000 } poll_next
timer not ready
SystemTime { tv_sec: 1579776488, tv_nsec: 548794000 } poll_next
timer ready
SystemTime { tv_sec: 1579776488, tv_nsec: 548882000 } yield

https://github.com/DoumanAsh/async-timer/blob/master/src/oneshot/kqueue.rs#L151 always not ready here
Which makes me wonder if tokio registered timer for write readiness.
Will need to check sources

from async-timer.

Hmm, I do remember having some odd issues with using PollEvented back in the day, and then ended up moving to Registration. I wonder if that might work here too?

from async-timer.

Conclusion: PollEvented might register non-read interest so we should either not use it or work it around by removing non-read interests

from async-timer.

Wait for tokio-rs/tokio#2222

from async-timer.

Fixed by tokio and will be available in 0.2.12

from async-timer.