net: Avoid race during io driver shutdown #2997
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To avoid IO resources getting registered while the driver is shutting down,`state: AtomicUsize` is introduced. Fixes: tokio-rs#2924
zaharidichev
commented
Oct 19, 2020
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| loop { | ||
| match self | ||
| .state | ||
| .compare_exchange(WAITING, REGISTERING, AcqRel, Acquire) | ||
| { | ||
| Ok(_) | Err(REGISTERING) => break, | ||
| Err(CLOSED) => return Err(io::Error::new(io::ErrorKind::Other, "reactor gone")), | ||
| _ => unreachable!(), | ||
| } |
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I have an uneasy feeling about this. Is it ok to spin like that here? Is there a better way to do it?
zaharidichev
changed the title
Darksonn
added
A-tokio
carllerche
reviewed
Oct 23, 2020
| io.wake(Ready::ALL); | ||
| }) | ||
| let inner = self.inner.take().expect("reactor closed"); | ||
| loop { |
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Generally spinning is not a great strategy as it will mess w/ schedulers.
|
Thanks for taking a stab at this 👍 The original issue ended up getting fixed as part of #2903. That said, my guess is we could improve the shutdown strategy more, but it will likely require rethinking some of how the i/o driver is structured. At this point, it probably isn't top priority. |
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To avoid IO resources getting registered while the driver
is shutting down,
state: AtomicUsizeis introduced.Motivation
As described in #2924 IO resources can be added while the driver is shutting down, resulting in these resources never being woken.
Solution
An atomic state is added that should ensure no IO resources are added while the driver is shutting down. ]
Fix #2924