kv: don't leak raft application tracing spans on or after ErrRemoved #54140
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Release justification: low risk, high benefit changes to existing functionality.
Fixes cockroachdb#53677. This commit ensures that we properly finish tracing spans of Raft commands that throw ErrRemoved errors in ApplySideEffects. I was originally intending to do something more dramatic and make `replicaStateMachine.ApplySideEffects` responsible for acknowledging proposers in all cases, but doing so turned out to be pretty invasive so I was concerned that it would be harder to backport to v20.2 and to v20.1. I may revisit that in the future. Release justification: low risk, high benefit changes to existing functionality.
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ajwerner
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Sep 9, 2020
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Defeat the linter and
Reviewed 1 of 1 files at r1, 2 of 2 files at r2, 8 of 8 files at r3.
Reviewable status:complete! 1 of 0 LGTMs obtained
pkg/kv/kvserver/apply/cmd.go, line 208 at r3 (raw file):
// In the following three functions, fn is written with ctx as a 2nd param // because callers wants to bind it to methods that has Commands (or variants)
“callers wants”
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Canceled. |
Extension of cockroachdb#53677. This commit ensures that we properly finish tracing spans of Raft commands that follow a command that throws a ErrRemoved. Before this commit, these commands would be abandoned and would never be finished. The effects of this are theoretically even worse than those fixed in the previous commit because these leaked commands could be locally proposed, so we may be abandoning a local proposer indefinitely. It's not clear that we ever saw an instance of this. It seems rare for a local proposal to end up in the same CommittedEntries batch as a command that removes a replica because of the lease requirements, but it doesn't seem impossible, especially of the local proposal was a RequestLease request. Release justification: low risk, high benefit changes to existing functionality.
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nvanbenschoten
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Sep 11, 2020
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TFTR!
bors r+
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pkg/kv/kvserver/apply/cmd.go, line 208 at r3 (raw file):
Previously, ajwerner wrote…
“callers wants”
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Done. Cleaned it up a bit too.
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This was referenced Sep 11, 2020
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Fixes #53677.
This change ensures that we properly finish tracing spans of Raft commands that throw ErrRemoved errors in ApplySideEffects. It then ensures that we properly finish tracing spans of Raft commands that follow a command that throws an
ErrRemoved. Before this, these commands would be abandoned and would never be finished. The effects of this are theoretically even worse than those fixed in the previous commit because these leaked commands could be locally proposed, so we may be abandoning a local proposer indefinitely.It's not clear that we ever saw an instance of this. It seems rare for a local proposal to end up in the same CommittedEntries batch as a command that removes a replica because of the lease requirements, but it doesn't seem impossible, especially of the local proposal was a RequestLease request.
I was originally intending to do something more dramatic and make
replicaStateMachine.ApplySideEffectsresponsible for acknowledging proposers in all cases, but doing so turned out to be pretty invasive so I was concerned that it would be harder to backport to v20.2 and to v20.1. I may revisit that in the future.Release justification: low risk, high benefit changes to existing functionality.