kvserver: fix trace span use-after-finish in apply pipeline #105877
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Reported internally[^1]. It's possible for a proposal to be inserted into the proposal buffer just before it is applied, and to be flushed when it is applied. In this case, we would, in `propBuf.FlushLockedWithRaftGroup`, log to the trace span, which is a problem since that span got finished when the proposal got applied. While this crash happened under `useReproposalsV2==true`, I'm unsure why this would be a new problem with `useReproposalsV2, and it doesn't seem to be particularly common either[^2]. However, I found a small gap in our handling of applied proposals, where one could actually show up in `FlushLockedWithRaftGroup` and explain this crash. I tightened the existing protections to drop the proposal before it reaches this point more reliably. Now we should no longer see this crash; if we did again, this would indicate a more serious problem in the trace span lifecycle. [^1]: https://cockroachlabs.slack.com/archives/C0KB9Q03D/p1688058044517609 [^2]: `./dev test --stress ./pkg/ccl/changefeedccl/ --filter TestChangefeedExactlyOnceExport --cpus 6`: 2456 runs so far, 0 failures, over 5m0s
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erikgrinaker
approved these changes
Jun 30, 2023
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TFTQR! bors r=erikgrinaker |
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Reported internally1. It's possible for a proposal to be inserted into the
proposal buffer just before it is applied, and to be flushed when it is
applied. In this case, we would, in
propBuf.FlushLockedWithRaftGroup, log tothe trace span, which is a problem since that span got finished when the
proposal got applied.
While this crash happened under
useReproposalsV2==true, I'm unsure why thiswould be a new problem with
useReproposalsV2, and it doesn't seem to beparticularly common either2. However, I found a small gap in our handling of
applied proposals, where one could actually show up in
FlushLockedWithRaftGroupand explain this crash.I tightened the existing protections to drop the proposal before it reaches
this point more reliably. Now we should no longer see this crash; if we did
again, this would indicate a more serious problem in the trace span lifecycle.
Epic: CRDB-25287
Release note: None
Footnotes
https://cockroachlabs.slack.com/archives/C0KB9Q03D/p1688058044517609 ↩
./dev test --stress ./pkg/ccl/changefeedccl/ --filter TestChangefeedExactlyOnceExport --cpus 6: 2456 runs so far, 0 failures, over 5m0s ↩