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Merged
Rustamchuk merged 1 commit into from
Jun 24, 2026
Merged

onfly sampling optimisation #2253

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11 changes: 9 additions & 2 deletions internal/agent/agent_shard_send.go
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Original file line number Diff line number Diff line change
Expand Up @@ -189,7 +189,7 @@ func (s *Shard) sampleBucket(bucket *data_model.MetricsBucket, sb *tlstatshouse.
var keptSizeSum int64
for m, stat := range bucket.CurStats {
if m == -1 {
for k, p := range stat.Partitions {
for k, p := range stat.Partitions { // only partitions map
p.SetSampleFactor()
if size := p.TopSize + p.TailSize; size > 0 {
sf := sfScratch[k.ID]
Expand All @@ -205,14 +205,21 @@ func (s *Shard) sampleBucket(bucket *data_model.MetricsBucket, sb *tlstatshouse.
sizeTraffic := uint32(0)
keptTraffic := uint32(0)
keptSize := uint32(0)
for _, p := range stat.Partitions {
f := func(p *data_model.BucketPartition) {
p.SetSampleFactor()
if p.TopSize != 0 || p.TailSize != 0 {
sizeTraffic += p.Traffic
keptTraffic += p.KeptTraffic
keptSize += p.TopSize + p.TailSize
}
}
if stat.Partition != nil {
f(stat.Partition)
} else {
for _, p := range stat.Partitions {
f(p)
}
}
sf := sfScratch[m]
if sizeTraffic > 0 {
sf[0] = float32(stat.Traffic) / float32(sizeTraffic) // global sf
Expand Down
149 changes: 94 additions & 55 deletions internal/data_model/bucket.go
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Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,7 @@ type (
BucketStat struct {
Traffic uint32
KeepSize uint32
Partition *BucketPartition // for fixed memory metric optimisation
Partitions map[PartitionKey]*BucketPartition // mostly len=1. len>1 for fairKey and others
}

Expand Down Expand Up @@ -327,76 +328,87 @@ func (b *MetricsBucket) SampleOrCreateMultiItem(rng *rand.Rand, key *Key, metric
}
keyString := unsafe.String(unsafe.SliceData(keyBytes), len(keyBytes))

sizes := b.CurSizes[metricID]
if sizes == nil {
sizes = map[string]*BucketSizeItem{}
b.CurSizes[metricID] = sizes
}
created = true
if size, ok := sizes[keyString]; ok {
keyString = size.key // use old keystring
b.keysBuffer = b.keysBuffer[:wasLen]
created = false
}

root := b.CurStats[budgetID]
if root == nil {
root = &BucketStat{Partitions: map[PartitionKey]*BucketPartition{}}
b.CurStats[budgetID] = root
}
decisionKey := samplingDecisionKey(key, metricInfo, metricID, budgetID)
part, ok := root.Partitions[decisionKey]
if !ok {
sf := float64(1)
part = &BucketPartition{SF: &sf, Tail: map[string]*MultiItem{}, Top: map[string]*MultiItem{}}
root.Partitions[decisionKey] = part
var part *BucketPartition
if decisionKey.ID == 0 { // no-map optimisation
if root.Partition == nil {
sf := float64(1)
root.Partition = &BucketPartition{SF: &sf, Tail: map[string]*MultiItem{}, Top: map[string]*MultiItem{}}
}
part = root.Partition
} else {
part = root.Partitions[decisionKey]
if part == nil {
sf := float64(1)
part = &BucketPartition{SF: &sf, Tail: map[string]*MultiItem{}, Top: map[string]*MultiItem{}}
root.Partitions[decisionKey] = part
}
}

size := uint32(key.TLSizeEstimate(key.Timestamp))
if created {
sizes[keyString] = &BucketSizeItem{key: keyString, Size: size}
}
part.Traffic += size
root.Traffic += size
itemSize := uint32(key.TLSizeEstimate(key.Timestamp))
part.Traffic += itemSize
root.Traffic += itemSize

if item = part.Top[keyString]; item != nil {
item.Count += count
item.DupCnt++
part.KeptTraffic += item.Size
return item, created
b.keysBuffer = b.keysBuffer[:wasLen]
return item, false
}
if item = part.Tail[keyString]; item != nil {
item.Count += count
if b.sampleTop(rng, part, part.Budget/2, keyString, item, item.Count) { // try move to top
if v := b.sampleTop(rng, part, part.Budget/2, &item.Key, item.MetricMeta, keyString, item, item.Count, item.Size); v != nil { // try move to top
b.removeTail(part, keyString, false)
} else {
} else if item.Size != 0 {
item.DupCnt++
part.KeptTraffic += item.Size
} else { // we could full lose it after sample
return nil, false
}
return item, created
b.keysBuffer = b.keysBuffer[:wasLen]
return item, false
}
item = &MultiItem{Key: *key, Size: size, SF: 1, GlobalSF: part.SF, Count: count, MetricMeta: metricInfo}

part.Budget = budget
if len(root.Partitions) > 0 {
part.Budget = uint32(math.Round(float64(budget) / float64(len(root.Partitions))))
sizes := b.CurSizes[metricID]
if sizes == nil {
sizes = map[string]*BucketSizeItem{}
b.CurSizes[metricID] = sizes
}
halfBudget := uint32(math.Round(float64(part.Budget) / 2))
if root.KeepSize < budget {
halfBudget = budget // get full root budget, until fit budget
created = true
if size, ok := sizes[keyString]; ok {
keyString = size.key // use old keystring
b.keysBuffer = b.keysBuffer[:wasLen]
created = false
} else {
sizes[keyString] = &BucketSizeItem{key: keyString, Size: itemSize}
}

part.Budget = budget
halfBudget := budget // get full root budget, until fit budget
if root.KeepSize >= budget {
if len(root.Partitions) > 0 {
part.Budget = uint32(math.Round(float64(budget) / float64(len(root.Partitions))))
}
halfBudget = uint32(math.Round(float64(part.Budget) / 2))
}

root.KeepSize -= part.TopSize + part.TailSize
if b.sampleTop(rng, part, halfBudget, keyString, item, count) {
if item = b.sampleTop(rng, part, halfBudget, key, metricInfo, keyString, nil, count, itemSize); item != nil { // not create item if sample optimisation
root.KeepSize += part.TopSize + part.TailSize
root.recalc(rng, b, budget, part.Budget)
return
return item, created
}
root.KeepSize += part.TopSize
if b.sampleTail(rng, part, halfBudget, keyString, item) {
if item = b.sampleTail(rng, part, halfBudget, key, metricInfo, keyString, nil, count, itemSize); item != nil { // not create item if sample optimisation
root.KeepSize += part.TailSize
root.recalc(rng, b, budget, part.Budget)
return
return item, created
}
root.KeepSize += part.TailSize
return nil, created
Expand All @@ -411,12 +423,12 @@ func (p *BucketPartition) SetSampleFactor() {
}

func (s *BucketStat) recalc(rng *rand.Rand, b *MetricsBucket, totalBudget, partBudget uint32) {
for _, p := range s.Partitions {
if totalBudget >= s.KeepSize {
return // do not delete everything
}
f := func(p *BucketPartition) {
if p.TopSize+p.TailSize < partBudget*2 {
continue // no need recalc
}
if totalBudget >= s.KeepSize {
break // do not delete everything
return // no need recalc
}
p.Budget = partBudget
halfBudget := uint32(math.Round(float64(partBudget) / 2))
Expand All @@ -432,13 +444,27 @@ func (s *BucketStat) recalc(rng *rand.Rand, b *MetricsBucket, totalBudget, partB
s.KeepSize += p.TopSize
s.KeepSize += p.TailSize
}
if s.Partition != nil {
f(s.Partition)
return
}
for _, p := range s.Partitions {
f(p)
if totalBudget >= s.KeepSize {
break // do not delete everything
}
}
}

func samplingDecisionKey(key *Key, metricInfo *format.MetricMetaValue, metricID, budgetID int32) PartitionKey {
var pk = PartitionKey{ID: metricID}
if budgetID == -1 || metricInfo == nil || len(metricInfo.FairKeyIndex) == 0 {
return pk
if budgetID == -1 {
return PartitionKey{ID: metricID}
} // no fair logic for common metrics
if metricInfo == nil || len(metricInfo.FairKeyIndex) == 0 {
return PartitionKey{}
}

var pk = PartitionKey{ID: metricID}
n := min(len(metricInfo.FairKeyIndex), maxFairKeyLen)
for i := 0; i < n; i++ {
if x := metricInfo.FairKeyIndex[i]; 0 <= x && x < len(key.Tags) {
Expand All @@ -448,10 +474,13 @@ func samplingDecisionKey(key *Key, metricInfo *format.MetricMetaValue, metricID,
return pk
}

func (b *MetricsBucket) sampleTail(rng *rand.Rand, part *BucketPartition, budget uint32, keyString string, item *MultiItem) bool {
func (b *MetricsBucket) sampleTail(rng *rand.Rand, part *BucketPartition, budget uint32, key *Key, meta *format.MetricMetaValue, keyString string, item *MultiItem, count float64, size uint32) *MultiItem {
if part.Traffic > budget && rng.Float64()*float64(part.Traffic) >= float64(budget) {
b.removeTail(part, keyString, true)
return false
return nil
}
if item == nil {
item = &MultiItem{Key: *key, Size: size, SF: 1, GlobalSF: part.SF, Count: count, MetricMeta: meta}
}
part.TailSize += item.Size
item.DupCnt++
Expand All @@ -461,7 +490,10 @@ func (b *MetricsBucket) sampleTail(rng *rand.Rand, part *BucketPartition, budget
for part.TailSize > budget && len(part.Tail) != 0 {
b.removeRandomTail(part)
}
return part.Tail[keyString] == item
if item.Size == 0 { // removeRandomTail could remove item
return nil
}
return item
}

func (b *MetricsBucket) removeRandomTail(part *BucketPartition) {
Expand Down Expand Up @@ -489,26 +521,33 @@ func (b *MetricsBucket) removeTail(part *BucketPartition, key string, fullDelete
} else {
part.KeptTraffic -= traffic
}
item.Size = 0 // optimisation to avoid map lookup
delete(b.MultiItems, key)
}
}

func (b *MetricsBucket) sampleTop(rng *rand.Rand, part *BucketPartition, budget uint32, key string, item *MultiItem, count float64) bool {
func (b *MetricsBucket) sampleTop(rng *rand.Rand, part *BucketPartition, budget uint32, key *Key, meta *format.MetricMetaValue, keyString string, item *MultiItem, count float64, size uint32) *MultiItem {
sf := 1 << part.TopSfLog2
if part.TopSfLog2 != 0 && count < float64(sf) {
if rng.Float64()*float64(sf) >= count {
return false
return nil
}
}
if item == nil {
item = &MultiItem{Key: *key, Size: size, SF: 1, GlobalSF: part.SF, Count: count, MetricMeta: meta}
}
part.TopSize += item.Size
item.DupCnt++
part.KeptTraffic += item.Size
part.Top[key] = item
b.MultiItems[key] = item
part.Top[keyString] = item
b.MultiItems[keyString] = item
for part.TopSize > budget && len(part.Top) != 0 {
part.resampleTop(rng, b, budget)
}
return part.Top[key] == item || part.Tail[key] == item // resampleTop could drop item to tail
if item.Size == 0 { // resampleTop could drop item to tail
return nil
}
return item
}

func (p *BucketPartition) resampleTop(rng *rand.Rand, b *MetricsBucket, tailBudget uint32) {
Expand All @@ -535,7 +574,7 @@ func (p *BucketPartition) resampleTop(rng *rand.Rand, b *MetricsBucket, tailBudg
p.KeptTraffic -= v.Size
}
delete(p.Top, k)
b.sampleTail(rng, p, tailBudget, k, v) // move to tail
b.sampleTail(rng, p, tailBudget, &v.Key, v.MetricMeta, k, v, v.Count, v.Size) // move to tail
if i++; i >= was/2 {
return // for remain low items
}
Expand Down
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