release-23.1: kv/concurrency: compute contention event duration from (key,txn) wait start time #99928
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… start time Fixes #98104. This commit resolves the bug identified in #98104 where multiple contention events could be emitted with overlapping durations, such that when these durations were added together (e.g. by `GetCumulativeContentionTime`), their sum was larger than the runtime of the entire query. This was possible because as of 70ef641, we were failing to reset the waiting start time on each new lock holder transaction for the same key. This commit fixes this by computing the contention event duration using `contentionTag.waitStart` instead of `waitingState.lockWaitStart`. It also cleans up some of this code and makes it harder to make such a mistake in the future. Release note: None
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LGTM
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complete! 0 of 0 LGTMs obtained (waiting on @AlexTalks and @nvanbenschoten)
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Backport 1/1 commits from #99166 on behalf of @nvanbenschoten.
/cc @cockroachdb/release
Fixes #98104.
This commit resolves the bug identified in #98104 where multiple contention events could be emitted with overlapping durations, such that when these durations were added together (e.g. by
GetCumulativeContentionTime), their sum was larger than the runtime of the entire query. This was possible because as of 70ef641, we were failing to reset the waiting start time on each new lock holder transaction for the same key.This commit fixes this by computing the contention event duration using
contentionTag.waitStartinstead ofwaitingState.lockWaitStart. It also cleans up some of this code and makes it harder to make such a mistake in the future.Release note: None
Release justification: observability fix