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kv/kvserver: TestStrictGCEnforcement failed about cockroach HOT 1 CLOSED

cockroach-teamcity commented on August 16, 2024

kv/kvserver: TestStrictGCEnforcement failed

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Comments (1)

arulajmani commented on August 16, 2024

I think this is a flake caused by a lease transfer. We see a lease transfer happen around the time the test fails:

I240318 20:59:40.329316 24933 13@kv/kvserver/lease_queue.go:132 â‹® [T1,Vsystem,n1,lease,s1,r68/1:â€¹/{Table/104-Max}â€º] 25  transferring lease to s2 usage=[batches/s=0.8 request_cpu/s=194Âµs raft_cpu/s=85Âµs write(keys)/s=0.9 write(bytes)/s=67 B read(keys)/s=0.2 read(bytes)/s=9 B]

The relevant commentary around how this can causes us to not strictly enforce the GC TTL is around:

cockroach/pkg/kv/kvserver/replica.go

Lines 1336 to 1347 in d8c1276

 // In order to make this check inexpensive, we keep a copy of the reading of 

 // protected timestamp state in the replica. This state may be stale, may not 

 // exist, or may be unusable given the current lease status. In those cases we 

 // must return the GC threshold. On the one hand this seems like a big deal, 

 // after a lease transfer, for minutes, users will be able to read data that 

 // has technically expired. Fortunately this strict enforcement is merely a 

 // user experience win; it's always safe to allow reads to continue so long 

 // as they are after the GC threshold. 

 c := r.mu.cachedProtectedTS 

 if st.State != kvserverpb.LeaseState_VALID || c.readAt.Less(st.Lease.Start.ToTimestamp()) { 

 return *r.mu.state.GCThreshold 

 }

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	// In order to make this check inexpensive, we keep a copy of the reading of
	// protected timestamp state in the replica. This state may be stale, may not
	// exist, or may be unusable given the current lease status. In those cases we
	// must return the GC threshold. On the one hand this seems like a big deal,
	// after a lease transfer, for minutes, users will be able to read data that
	// has technically expired. Fortunately this strict enforcement is merely a
	// user experience win; it's always safe to allow reads to continue so long
	// as they are after the GC threshold.
	c := r.mu.cachedProtectedTS
	if st.State != kvserverpb.LeaseState_VALID \|\| c.readAt.Less(st.Lease.Start.ToTimestamp()) {
	return *r.mu.state.GCThreshold
	}