Increase scheduler worker cancellation chan cap #741
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With previous implementation, if worker was busy talking to scheduler, we didn't push the cancellation, keeping that query running. When cancelling a query, all its subqueries are cancelled at the same time, so this was most likely happening all the time (first subquery scheduled on this worker was canceled, the rest were not because worker was busy cancelling the first one). Also removed the `<-ctx.Done()` escape point when waiting for the enqueueing ACK and modified the enqueueing method to ensure that it always responds something. Fixes: #740 Inspired by: grafana/loki#5113 Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
colega
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Jan 13, 2022
When scheduler worker is handling requests, if there's certain pressure on the loop, we can keep enqueueing requests instead of handling the cancellations. However, when there's that pressure on the loop, it's more important than never to properly cancel the requests. This checks the cancellations channel first, and then checks the requests channel too. Related to #741 Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
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Co-authored-by: Peter Štibraný <peter.stibrany@grafana.com>
pstibrany
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Jan 13, 2022
Co-authored-by: Peter Štibraný <peter.stibrany@grafana.com>
Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
Signed-off-by: Oleg Zaytsev <mail@olegzaytsev.com>
pstibrany
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Jan 14, 2022
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Thanks Oleg ! and well done @kavirajk for finding this issue. |
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What this PR does:
With previous implementation, if worker was busy talking to scheduler, we didn't push the cancellation, keeping that query running.
When cancelling a query, all its subqueries are cancelled at the same time, so this was most likely happening all the time (first subquery scheduled on this worker was canceled, the rest were not because worker was busy cancelling the first one).
Also removed the
<-ctx.Done()escape point when waiting for the enqueueing ACK and modified the enqueueing method to ensure that it always responds something.Which issue(s) this PR fixes:
Fixes: #740
Inspired by: grafana/loki#5113
Checklist
CHANGELOG.mdupdated - the order of entries should be[CHANGE],[FEATURE],[ENHANCEMENT],[BUGFIX]