time: update wake_up while holding all the locks of sharded time wheels #6683
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Could we add a loom test for this?
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I will try to add a loom test for this one.
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Is this an actual data race or just a race condition? It looks like it's just incorrect usage of locks, not any incorrect unsafe code.
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It seems that I have confused them. I would like to modify the title to time: update wake_up while holding all the locks of sharded time wheels.
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| let locks = (0..rt_handle.time().inner.get_shard_size()) | ||
| .map(|id| rt_handle.time().inner.lock_sharded_wheel(id)) | ||
| .collect::<Vec<_>>(); |
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It would be nice to avoid allocating this vector every time.
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Do you have any ideas to achieve this? Can we use smallvec::SmallVec here?
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We're not going to introduce a new dependency for it, but maybe a solution like that could work. But I don't think it has to be solved before we publish a release containing this fix.
(See also chat on discord.)
I'm sorry for the delay here, I've had a very busy weekend, maybe I'll get around to getting this done today. |
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Bumps tokio from 1.38.0 to 1.38.1. Release notes Sourced from tokio's releases. Tokio v1.38.1 1.38.1 (July 16th, 2024) This release fixes the bug identified as (#6682), which caused timers not to fire when they should. Fixed time: update wake_up while holding all the locks of sharded time wheels (#6683) #6682: tokio-rs/tokio#6682 #6683: tokio-rs/tokio#6683 Commits 14b9f71 chore: release Tokio v1.38.1 (#6688) 24344df time: fix race condition leading to lost timers (#6683) See full diff in compare view Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase. Dependabot commands and options You can trigger Dependabot actions by commenting on this PR: @dependabot rebase will rebase this PR @dependabot recreate will recreate this PR, overwriting any edits that have been made to it @dependabot merge will merge this PR after your CI passes on it @dependabot squash and merge will squash and merge this PR after your CI passes on it @dependabot cancel merge will cancel a previously requested merge and block automerging @dependabot reopen will reopen this PR if it is closed @dependabot close will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually @dependabot show <dependency name> ignore conditions will show all of the ignore conditions of the specified dependency @dependabot ignore this major version will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself) @dependabot ignore this minor version will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself) @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)
Motivation
fixes #6682
We may encounter the following issue:
expiration_timeisNone, we did not update thenext_wakeimmediately. Thenext_wakeis now the old value of the previous round ofpark_internal(the value is notNone). Then we droped the locks.Sleep, they find thatwhen > next_wake(herenext_wakeis notNone), so they will not executeunpark.unpark().Solution
While we hold the locks, we calculate and update the
next_wake.