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shouldn't try leader first when leader's store is slow in prefer-leader strategy in replicaSelectorV2 (#1215) 

* shouldn't try leader first when leader's store is slow in prefer-leader strategy in replicaSelectorV2

Signed-off-by: crazycs520 <crazycs520@gmail.com>

* refine comment

Signed-off-by: crazycs520 <crazycs520@gmail.com>

* refine comment

Signed-off-by: crazycs520 <crazycs520@gmail.com>

* fix bug and add test

Signed-off-by: crazycs520 <crazycs520@gmail.com>

---------

Signed-off-by: crazycs520 <crazycs520@gmail.com>
This commit is contained in:
crazycs 2024-03-12 19:59:37 +08:00 committed by GitHub
parent 3e419e68aa
commit 0416875f55
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2 changed files with 102 additions and 16 deletions
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13
internal/locate/replica_selector.go
View File

@ -298,6 +298,11 @@ func (s *ReplicaSelectMixedStrategy) isCandidate(r *replica, isLeader bool, epoc
if s.busyThreshold > 0 && (r.store.EstimatedWaitTime() > s.busyThreshold || r.serverIsBusy || isLeader) {
return false
}
if s.preferLeader && r.store.healthStatus.IsSlow() && !isLeader {
// This logic is used to compatible with old replica selector.
// When use prefer-leader strategy, if the replica is slow, and it's not leader, then it is not candidate, skip it.
return false
}
return true
}
@ -320,7 +325,13 @@ func (s *ReplicaSelectMixedStrategy) calculateScore(r *replica, isLeader bool) i
}
if isLeader {
if s.preferLeader {
score |= flagPreferLeader
// Following logic is used to compatible with old replica selector.
// When use prefer-leader strategy, only prefer leader when the leader's store is not slow.
if !r.store.healthStatus.IsSlow() {
score |= flagPreferLeader
} else {
score |= flagNormalPeer
}
} else if s.tryLeader {
if len(s.labels) > 0 {
// When the leader has matching labels, prefer leader than other mismatching peers.

105
internal/locate/replica_selector_test.go
View File

@ -180,11 +180,7 @@ func TestReplicaSelectorCalculateScore(t *testing.T) {
s.Equal(score, flagLabelMatches+flagNormalPeer+flagNotAttempt)
strategy.preferLeader = true
score = strategy.calculateScore(r, isLeader)
if isLeader {
s.Equal(score, flagLabelMatches+flagPreferLeader+flagNotAttempt)
} else {
s.Equal(score, flagLabelMatches+flagNormalPeer+flagNotAttempt)
}
s.Equal(score, flagLabelMatches+flagNormalPeer+flagNotAttempt)
strategy.learnerOnly = true
strategy.tryLeader = false
strategy.preferLeader = false
@ -218,18 +214,10 @@ func TestReplicaSelectorCalculateScore(t *testing.T) {
labels: labels,
}
score = strategy.calculateScore(r, isLeader)
if isLeader {
s.Equal(score, flagPreferLeader+flagNotAttempt)
} else {
s.Equal(score, flagNormalPeer+flagNotAttempt)
}
s.Equal(score, flagNormalPeer+flagNotAttempt)
r.store.labels = labels
score = strategy.calculateScore(r, isLeader)
if isLeader {
s.Equal(score, flagLabelMatches+flagPreferLeader+flagNotAttempt)
} else {
s.Equal(score, flagLabelMatches+flagNormalPeer+flagNotAttempt)
}
s.Equal(score, flagLabelMatches+flagNormalPeer+flagNotAttempt)
r.store.labels = nil
}
}
@ -1658,6 +1646,93 @@ func TestReplicaReadAccessPathByMixedAndPreferLeaderCase(t *testing.T) {
}
s.True(s.runCaseAndCompare(ca))
s.changeRegionLeader(1)
cas := []replicaSelectorAccessPathCase{
{
reqType: tikvrpc.CmdGet,
readType: kv.ReplicaReadPreferLeader,
staleRead: false,
timeout: 0,
accessErr: []RegionErrorType{ServerIsBusyErr},
expect: &accessPathResult{
accessPath: []string{
"{addr: store1, replica-read: true, stale-read: false}", // store1 will be marked already slow.
"{addr: store2, replica-read: true, stale-read: false}",
},
respErr: "",
respRegionError: nil,
backoffCnt: 0,
backoffDetail: []string{},
regionIsValid: true,
},
afterRun: func() { /* don't invalid region */ },
},
{
reqType: tikvrpc.CmdGet,
readType: kv.ReplicaReadPreferLeader,
staleRead: false,
timeout: 0,
accessErr: []RegionErrorType{ServerIsBusyErr, ServerIsBusyErr, ServerIsBusyErr},
beforeRun: func() { /* don't resetStoreState */ },
expect: &accessPathResult{
accessPath: []string{
"{addr: store2, replica-read: true, stale-read: false}", // won't try leader in store1, since it is slow.
"{addr: store3, replica-read: true, stale-read: false}",
"{addr: store1, replica-read: true, stale-read: false}",
},
respErr: "",
respRegionError: fakeEpochNotMatch,
backoffCnt: 1,
backoffDetail: []string{"tikvServerBusy+1"},
regionIsValid: false,
},
},
}
s.True(s.runMultiCaseAndCompare(cas))
cas = []replicaSelectorAccessPathCase{
{
reqType: tikvrpc.CmdGet,
readType: kv.ReplicaReadPreferLeader,
staleRead: false,
timeout: 0,
accessErr: []RegionErrorType{ServerIsBusyErr, ServerIsBusyErr},
expect: &accessPathResult{
accessPath: []string{
"{addr: store1, replica-read: true, stale-read: false}", // store1 will be marked already slow.
"{addr: store2, replica-read: true, stale-read: false}", // store2 will be marked already slow.
"{addr: store3, replica-read: true, stale-read: false}",
},
respErr: "",
respRegionError: nil,
backoffCnt: 0,
backoffDetail: []string{},
regionIsValid: true,
},
afterRun: func() { /* don't invalid region */ },
},
{
reqType: tikvrpc.CmdGet,
readType: kv.ReplicaReadPreferLeader,
staleRead: false,
timeout: 0,
accessErr: []RegionErrorType{ServerIsBusyErr, ServerIsBusyErr, ServerIsBusyErr},
beforeRun: func() { /* don't resetStoreState */ },
expect: &accessPathResult{
accessPath: []string{
"{addr: store3, replica-read: true, stale-read: false}", // won't try leader in store1, since it is slow, ditto for store2.
"{addr: store1, replica-read: true, stale-read: false}",
// won't retry store2, since it is slow, and it is not leader replica.
},
respErr: "",
respRegionError: fakeEpochNotMatch,
backoffCnt: 1,
backoffDetail: []string{"tikvServerBusy+1"},
regionIsValid: false,
},
},
}
s.True(s.runMultiCaseAndCompare(cas))
}
func TestReplicaReadAccessPathByStaleReadCase(t *testing.T) {