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Merge pull request #194 from bilibili/library/bbr-prev-drop-optimization

修复自适应限流在 cpu 抖动后,可能出现限流过激的问题
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Tony 2019-07-03 10:09:55 +08:00 committed by GitHub
commit a6cc978bdf
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2 changed files with 15 additions and 5 deletions

View File

@ -17,10 +17,10 @@ import (
var (
cpu int64
decay = 0.75
decay = 0.95
defaultConf = &Config{
Window: time.Second * 5,
WinBucket: 50,
Window: time.Second * 10,
WinBucket: 100,
CPUThreshold: 800,
}
)
@ -31,6 +31,7 @@ func init() {
go cpuproc()
}
// cpu = cpuᵗ⁻¹ * decay + cpuᵗ * (1 - decay)
func cpuproc() {
ticker := time.NewTicker(time.Millisecond * 250)
defer func() {
@ -136,7 +137,11 @@ func (l *BBR) shouldDrop() bool {
}
return false
}
return inFlight > 1 && inFlight > maxInflight
drop := inFlight > 1 && inFlight > maxInflight
if drop {
atomic.StoreInt64(&l.prevDrop, time.Now().Unix())
}
return drop
}
// Stat tasks a snapshot of the bbr limiter.
@ -158,7 +163,6 @@ func (l *BBR) Allow(ctx context.Context, opts ...limit.AllowOption) (func(info l
opt.Apply(&allowOpts)
}
if l.shouldDrop() {
atomic.StoreInt64(&l.prevDrop, time.Now().Unix())
return nil, ecode.LimitExceed
}
atomic.AddInt64(&l.inFlight, 1)

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@ -145,7 +145,13 @@ func TestBBRShouldDrop(t *testing.T) {
bbr.inFlight = 80
assert.Equal(t, true, bbr.shouldDrop())
// cpu < 800, inflight > maxQps, cold duration
cpu = 700
bbr.inFlight = 80
assert.Equal(t, true, bbr.shouldDrop())
// cpu < 800, inflight > maxQps
time.Sleep(2 * time.Second)
cpu = 700
bbr.inFlight = 80
assert.Equal(t, false, bbr.shouldDrop())