kv: detect context cancellation in limitBulkIOWrite, avoid log spam #73279
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This commit adds logic to propagate context cancellation in `limitBulkIOWrite`. This function is used in two places, 1) when ingesting ssts, and 2) when receiving a snapshot. The first case uses the Raft scheduler goroutine's context, so it never gets cancelled. The second case uses the context of the sender of a Raft snapshot, so it can get cancelled. In customer clusters, we were seeing Raft snapshots hit their deadline and begin spamming `error rate limiting bulk io write: context deadline exceeded` errors messages. This was bad for two reasons. First, it was very noisy. Second, it meant that a Raft snapshot that was no longer going to succeed was still writing out full SSTs while holding on to the `snapshotApplySem`. This contributed to the snapshot starvation we saw in the issue. With this commit, `limitBulkIOWrite` will eagerly detect context cancellation and will propagate the cancellation up to the caller, allowing the caller to quickly release resources. Release notes (bug fix): Raft snapshots now detect timeouts earlier and avoid spamming the logs with `context deadline exceeded` errors.
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tbg
approved these changes
Nov 30, 2021
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Reviewed 4 of 4 files at r1, all commit messages.
Reviewable status:complete! 0 of 0 LGTMs obtained (waiting on @dt and @erikgrinaker)
erikgrinaker
approved these changes
Nov 30, 2021
dt
approved these changes
Nov 30, 2021
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TFTRs! bors r+ |
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This commit adds logic to propagate context cancellation in
limitBulkIOWrite.This function is used in two places, 1) when ingesting ssts, and 2) when
receiving a snapshot. The first case uses the Raft scheduler goroutine's
context, so it never gets cancelled. The second case uses the context of the
sender of a Raft snapshot, so it can get cancelled.
In customer clusters, we were seeing Raft snapshots hit their deadline and begin
spamming
error rate limiting bulk io write: context deadline exceedederrorsmessages. This was bad for two reasons. First, it was very noisy. Second, it
meant that a Raft snapshot that was no longer going to succeed was still writing
out full SSTs while holding on to the
snapshotApplySem. This contributed tothe snapshot starvation we saw in the issue.
With this commit,
limitBulkIOWritewill eagerly detect context cancellationand will propagate the cancellation up to the caller, allowing the caller to
quickly release resources.
Release notes (bug fix): Raft snapshots now detect timeouts earlier and avoid
spamming the logs with
context deadline exceedederrors.