Break poll loop out into subroutine guaranteed to quit before producer stop#941
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💯, this definitely looks like the cause. Nice fix! 🎉
…r stop This one's aimed at fixing the race detector failure as observed in [1]. Honestly, I couldn't repro this locally even at 1,000 iteration, but reading the code, I'm pretty sure I know what the problem is. The `fetchAndRunLoop` would start a separate goroutine that'd use a timer to trigger a poll at `FetchPollInterval` so that fetches are occasionally performed even if listen/notify missed something. This inner goroutine would stop on context cancellation, but it wasn't guaranteed to return before a stop finished. Therefore, as the stress test called `Start` again, `fetchLimiter` could be modified while the goroutine was still accessing it from the last run of the producer. Fix this by making the fetch loop a "subroutine", which is a convention used already for other goroutines in `Start`. `Start` waits on all these goroutines to finish before completing a stop, therefore guaranteeing that the next iteration of `Start` can do so safely. [1] https://github.com/riverqueue/river/actions/runs/15419505042/job/43390545084
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Thanks! And oops — a few typos in titles/description that are fixed now. |
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This one's aimed at fixing the race detector failure as observed in [1].
Honestly, I couldn't repro this locally even at 1,000 iteration, but
reading the code, I'm pretty sure I know what the problem is.
The
fetchAndRunLoopwould start a separate goroutine that'd use atimer to trigger a poll at
FetchPollIntervalso that fetches areoccasionally performed even if listen/notify missed something. This
inner goroutine would stop on context cancellation, but it wasn't
guaranteed to return before a stop finished. Therefore, as the stress
test called
Startagain,fetchLimitercould be modified while thegoroutine was still accessing it from the last run of the producer.
Fix this by making the fetch loop a "subroutine", which is a convention
used already for other goroutines in
Start.Startwaits on all thesegoroutines to finish before completing a stop, therefore guaranteeing
that the next iteration of
Startcan do so safely.[1] https://github.com/riverqueue/river/actions/runs/15419505042/job/43390545084