Stale Read checks include comparing node's Applied Index with Leader Commit Index #1673
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otoolep
changed the title
aderouineau
reviewed
Feb 6, 2024
store/store.go
Outdated
| @@ -1806,7 +1807,8 @@ func (s *Store) isStaleRead(freshness int64) bool { | |||
| if freshness == 0 || s.raft.State() == raft.Leader { | |||
| return false | |||
| } | |||
| return time.Since(s.raft.LastContact()).Nanoseconds() > freshness | |||
| return time.Since(s.raft.LastContact()).Nanoseconds() > freshness && | |||
| s.raft.CommitIndex() == s.DBAppliedIndex() | |||
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Having s.raft.CommitIndex() == s.DBAppliedIndex() makes the condition too strict, especially for large updates that can still finish within the allowed freshness.
Could we instead add aTime field in Store that gets updated to LastContact when there is no new index, and when there is, to whenever the index gets applied?
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I noticed s.DBAppliedIndex() is protected by a mutex. Would it make sense to replace it with a https://pkg.go.dev/sync/atomic#Uint64?
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Yeah, you're the second person to suggest this. @jtackaberry did too.
Makes sense, but I'll do that in a separate PR.
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