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raft: lower split vote rate

release-3.0
Xiang Li 2016-04-01 10:09:09 -07:00
parent bf6d905a5a
commit 5d431b4782
3 changed files with 26 additions and 18 deletions
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30
raft/raft.go
View File

@ -176,9 +176,14 @@ type raft struct {
heartbeatTimeout int heartbeatTimeout int
electionTimeout int electionTimeout int
rand *rand.Rand // randomizedElectionTimeout is a random number between
tick func() // [electiontimeout, 2 * electiontimeout - 1]. It gets reset
step stepFunc // when raft changes its state to follower or candidate.
randomizedElectionTimeout int
rand *rand.Rand
tick func()
step stepFunc
logger Logger logger Logger
} }
@ -392,6 +397,7 @@ func (r *raft) reset(term uint64) {
r.electionElapsed = 0 r.electionElapsed = 0
r.heartbeatElapsed = 0 r.heartbeatElapsed = 0
r.resetRandomizedElectionTimeout()
r.votes = make(map[uint64]bool) r.votes = make(map[uint64]bool)
for id := range r.prs { for id := range r.prs {
@ -422,7 +428,7 @@ func (r *raft) tickElection() {
return return
} }
r.electionElapsed++ r.electionElapsed++
if r.isElectionTimeout() { if r.pastElectionTimeout() {
r.electionElapsed = 0 r.electionElapsed = 0
r.Step(pb.Message{From: r.id, Type: pb.MsgHup}) r.Step(pb.Message{From: r.id, Type: pb.MsgHup})
} }
@ -863,15 +869,15 @@ func (r *raft) loadState(state pb.HardState) {
r.Vote = state.Vote r.Vote = state.Vote
} }
// isElectionTimeout returns true if r.electionElapsed is greater than the // pastElectionTimeout returns true if r.electionElapsed is greater than the
// randomized election timeout in (electiontimeout, 2 * electiontimeout - 1). // randomized election timeout in [electiontimeout, 2 * electiontimeout - 1].
// Otherwise, it returns false. // Otherwise, it returns false.
func (r *raft) isElectionTimeout() bool { func (r *raft) pastElectionTimeout() bool {
d := r.electionElapsed - r.electionTimeout return r.electionElapsed >= r.randomizedElectionTimeout
if d < 0 { }
return false
} func (r *raft) resetRandomizedElectionTimeout() {
return d > r.rand.Int()%r.electionTimeout r.randomizedElectionTimeout = r.electionTimeout + r.rand.Int()%r.electionTimeout
} }
// checkQuorumActive returns true if the quorum is active from // checkQuorumActive returns true if the quorum is active from

4
raft/raft_paper_test.go
View File

@ -381,8 +381,8 @@ func testNonleadersElectionTimeoutNonconflict(t *testing.T, state StateType) {
} }
} }
if g := float64(conflicts) / 1000; g > 0.4 { if g := float64(conflicts) / 1000; g > 0.3 {
t.Errorf("probability of conflicts = %v, want <= 0.4", g) t.Errorf("probability of conflicts = %v, want <= 0.3", g)
} }
} }

10
raft/raft_test.go
View File

@ -754,9 +754,10 @@ func TestIsElectionTimeout(t *testing.T) {
round bool round bool
}{ }{
{5, 0, false}, {5, 0, false},
{13, 0.3, true}, {10, 0.1, true},
{15, 0.5, true}, {13, 0.4, true},
{18, 0.8, true}, {15, 0.6, true},
{18, 0.9, true},
{20, 1, false}, {20, 1, false},
} }
@ -765,7 +766,8 @@ func TestIsElectionTimeout(t *testing.T) {
sm.electionElapsed = tt.elapse sm.electionElapsed = tt.elapse
c := 0 c := 0
for j := 0; j < 10000; j++ { for j := 0; j < 10000; j++ {
if sm.isElectionTimeout() { sm.resetRandomizedElectionTimeout()
if sm.pastElectionTimeout() {
c++ c++
} }
} }