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lib/storage: sort tag filters by the number of loops they need for the execution

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This metric should work better than the filter execution duration, since it cannot be distorted
by concurrently running queries.
This commit is contained in:
Aliaksandr Valialkin 2021-02-18 12:47:36 +02:00
parent f95dd67a22
commit 711f8a5b8d
3 changed files with 85 additions and 89 deletions
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168
lib/storage/index_db.go
View File

@ -6,7 +6,6 @@ import (
"errors"
"fmt"
"io"
"math"
"path/filepath"
"sort"
"sync"
@ -2047,7 +2046,7 @@ func (is *indexSearch) getTagFilterWithMinMetricIDsCount(tfs *TagFilters, maxMet
continue
}
metricIDs, err := is.getMetricIDsForTagFilter(tf, nil, maxMetrics)
metricIDs, _, err := is.getMetricIDsForTagFilter(tf, nil, maxMetrics)
if err != nil {
if err == errFallbackToMetricNameMatch {
// Skip tag filters requiring to scan for too many metrics.
@ -2369,34 +2368,36 @@ const (
var uselessTagFilterCacheValue = []byte("1")
func (is *indexSearch) getMetricIDsForTagFilter(tf *tagFilter, filter *uint64set.Set, maxMetrics int) (*uint64set.Set, error) {
func (is *indexSearch) getMetricIDsForTagFilter(tf *tagFilter, filter *uint64set.Set, maxMetrics int) (*uint64set.Set, uint64, error) {
if tf.isNegative {
logger.Panicf("BUG: isNegative must be false")
}
metricIDs := &uint64set.Set{}
if len(tf.orSuffixes) > 0 {
// Fast path for orSuffixes - seek for rows for each value from orSuffixes.
if err := is.updateMetricIDsForOrSuffixesNoFilter(tf, maxMetrics, metricIDs); err != nil {
loopsCount, err := is.updateMetricIDsForOrSuffixesNoFilter(tf, maxMetrics, metricIDs)
if err != nil {
if err == errFallbackToMetricNameMatch {
return nil, err
return nil, loopsCount, err
}
return nil, fmt.Errorf("error when searching for metricIDs for tagFilter in fast path: %w; tagFilter=%s", err, tf)
return nil, loopsCount, fmt.Errorf("error when searching for metricIDs for tagFilter in fast path: %w; tagFilter=%s", err, tf)
}
return metricIDs, nil
return metricIDs, loopsCount, nil
}
// Slow path - scan for all the rows with the given prefix.
maxLoops := maxMetrics * maxIndexScanSlowLoopsPerMetric
if err := is.getMetricIDsForTagFilterSlow(tf, filter, maxLoops, metricIDs.Add); err != nil {
maxLoopsCount := uint64(maxMetrics) * maxIndexScanSlowLoopsPerMetric
loopsCount, err := is.getMetricIDsForTagFilterSlow(tf, filter, maxLoopsCount, metricIDs.Add)
if err != nil {
if err == errFallbackToMetricNameMatch {
return nil, err
return nil, loopsCount, err
}
return nil, fmt.Errorf("error when searching for metricIDs for tagFilter in slow path: %w; tagFilter=%s", err, tf)
return nil, loopsCount, fmt.Errorf("error when searching for metricIDs for tagFilter in slow path: %w; tagFilter=%s", err, tf)
}
return metricIDs, nil
return metricIDs, loopsCount, nil
}
func (is *indexSearch) getMetricIDsForTagFilterSlow(tf *tagFilter, filter *uint64set.Set, maxLoops int, f func(metricID uint64)) error {
func (is *indexSearch) getMetricIDsForTagFilterSlow(tf *tagFilter, filter *uint64set.Set, maxLoopsCount uint64, f func(metricID uint64)) (uint64, error) {
if len(tf.orSuffixes) > 0 {
logger.Panicf("BUG: the getMetricIDsForTagFilterSlow must be called only for empty tf.orSuffixes; got %s", tf.orSuffixes)
}
@ -2408,40 +2409,40 @@ func (is *indexSearch) getMetricIDsForTagFilterSlow(tf *tagFilter, filter *uint6
mp.Reset()
var prevMatchingSuffix []byte
var prevMatch bool
loops := 0
var loopsCount uint64
loopsPaceLimiter := 0
prefix := tf.prefix
ts.Seek(prefix)
for ts.NextItem() {
if loopsPaceLimiter&paceLimiterMediumIterationsMask == 0 {
if err := checkSearchDeadlineAndPace(is.deadline); err != nil {
return err
return loopsCount, err
}
}
loopsPaceLimiter++
item := ts.Item
if !bytes.HasPrefix(item, prefix) {
return nil
return loopsCount, nil
}
tail := item[len(prefix):]
n := bytes.IndexByte(tail, tagSeparatorChar)
if n < 0 {
return fmt.Errorf("invalid tag->metricIDs line %q: cannot find tagSeparatorChar=%d", item, tagSeparatorChar)
return loopsCount, fmt.Errorf("invalid tag->metricIDs line %q: cannot find tagSeparatorChar=%d", item, tagSeparatorChar)
}
suffix := tail[:n+1]
tail = tail[n+1:]
if err := mp.InitOnlyTail(item, tail); err != nil {
return err
return loopsCount, err
}
mp.ParseMetricIDs()
loopsCount += uint64(mp.MetricIDsLen())
if loopsCount > maxLoopsCount {
return loopsCount, errFallbackToMetricNameMatch
}
if prevMatch && string(suffix) == string(prevMatchingSuffix) {
// Fast path: the same tag value found.
// There is no need in checking it again with potentially
// slow tf.matchSuffix, which may call regexp.
loops += mp.MetricIDsLen()
if loops > maxLoops {
return errFallbackToMetricNameMatch
}
for _, metricID := range mp.MetricIDs {
if filter != nil && !filter.Has(metricID) {
continue
@ -2455,11 +2456,11 @@ func (is *indexSearch) getMetricIDsForTagFilterSlow(tf *tagFilter, filter *uint6
// since the current row has no matching metricIDs.
continue
}
// Slow path: need tf.matchSuffix call.
ok, err := tf.matchSuffix(suffix)
loopsCount += reMatchCost
if err != nil {
return fmt.Errorf("error when matching %s against suffix %q: %w", tf, suffix, err)
return loopsCount, fmt.Errorf("error when matching %s against suffix %q: %w", tf, suffix, err)
}
if !ok {
prevMatch = false
@ -2474,18 +2475,16 @@ func (is *indexSearch) getMetricIDsForTagFilterSlow(tf *tagFilter, filter *uint6
// The last char in kb.B must be tagSeparatorChar. Just increment it
// in order to jump to the next tag value.
if len(kb.B) == 0 || kb.B[len(kb.B)-1] != tagSeparatorChar || tagSeparatorChar >= 0xff {
return fmt.Errorf("data corruption: the last char in k=%X must be %X", kb.B, tagSeparatorChar)
return loopsCount, fmt.Errorf("data corruption: the last char in k=%X must be %X", kb.B, tagSeparatorChar)
}
kb.B[len(kb.B)-1]++
ts.Seek(kb.B)
// Assume that a seek cost is equivalent to 100 ordinary loops.
loopsCount += 100
continue
}
prevMatch = true
prevMatchingSuffix = append(prevMatchingSuffix[:0], suffix...)
loops += mp.MetricIDsLen()
if loops > maxLoops {
return errFallbackToMetricNameMatch
}
for _, metricID := range mp.MetricIDs {
if filter != nil && !filter.Has(metricID) {
continue
@ -2494,29 +2493,32 @@ func (is *indexSearch) getMetricIDsForTagFilterSlow(tf *tagFilter, filter *uint6
}
}
if err := ts.Error(); err != nil {
return fmt.Errorf("error when searching for tag filter prefix %q: %w", prefix, err)
return loopsCount, fmt.Errorf("error when searching for tag filter prefix %q: %w", prefix, err)
}
return nil
return loopsCount, nil
}
func (is *indexSearch) updateMetricIDsForOrSuffixesNoFilter(tf *tagFilter, maxMetrics int, metricIDs *uint64set.Set) error {
func (is *indexSearch) updateMetricIDsForOrSuffixesNoFilter(tf *tagFilter, maxMetrics int, metricIDs *uint64set.Set) (uint64, error) {
if tf.isNegative {
logger.Panicf("BUG: isNegative must be false")
}
kb := kbPool.Get()
defer kbPool.Put(kb)
var loopsCount uint64
for _, orSuffix := range tf.orSuffixes {
kb.B = append(kb.B[:0], tf.prefix...)
kb.B = append(kb.B, orSuffix...)
kb.B = append(kb.B, tagSeparatorChar)
if err := is.updateMetricIDsForOrSuffixNoFilter(kb.B, maxMetrics, metricIDs); err != nil {
return err
lc, err := is.updateMetricIDsForOrSuffixNoFilter(kb.B, maxMetrics, metricIDs)
if err != nil {
return loopsCount, err
}
loopsCount += lc
if metricIDs.Len() >= maxMetrics {
return nil
return loopsCount, nil
}
}
return nil
return loopsCount, nil
}
func (is *indexSearch) updateMetricIDsForOrSuffixesWithFilter(tf *tagFilter, metricIDs, filter *uint64set.Set) error {
@ -2534,39 +2536,39 @@ func (is *indexSearch) updateMetricIDsForOrSuffixesWithFilter(tf *tagFilter, met
return nil
}
func (is *indexSearch) updateMetricIDsForOrSuffixNoFilter(prefix []byte, maxMetrics int, metricIDs *uint64set.Set) error {
func (is *indexSearch) updateMetricIDsForOrSuffixNoFilter(prefix []byte, maxMetrics int, metricIDs *uint64set.Set) (uint64, error) {
ts := &is.ts
mp := &is.mp
mp.Reset()
maxLoops := maxMetrics * maxIndexScanLoopsPerMetric
loops := 0
maxLoopsCount := uint64(maxMetrics) * maxIndexScanLoopsPerMetric
var loopsCount uint64
loopsPaceLimiter := 0
ts.Seek(prefix)
for metricIDs.Len() < maxMetrics && ts.NextItem() {
if loopsPaceLimiter&paceLimiterFastIterationsMask == 0 {
if err := checkSearchDeadlineAndPace(is.deadline); err != nil {
return err
return loopsCount, err
}
}
loopsPaceLimiter++
item := ts.Item
if !bytes.HasPrefix(item, prefix) {
return nil
return loopsCount, nil
}
if err := mp.InitOnlyTail(item, item[len(prefix):]); err != nil {
return err
return loopsCount, err
}
loops += mp.MetricIDsLen()
if loops > maxLoops {
return errFallbackToMetricNameMatch
loopsCount += uint64(mp.MetricIDsLen())
if loopsCount > maxLoopsCount {
return loopsCount, errFallbackToMetricNameMatch
}
mp.ParseMetricIDs()
metricIDs.AddMulti(mp.MetricIDs)
}
if err := ts.Error(); err != nil {
return fmt.Errorf("error when searching for tag filter prefix %q: %w", prefix, err)
return loopsCount, fmt.Errorf("error when searching for tag filter prefix %q: %w", prefix, err)
}
return nil
return loopsCount, nil
}
func (is *indexSearch) updateMetricIDsForOrSuffixWithFilter(prefix []byte, metricIDs *uint64set.Set, sortedFilter []uint64, isNegative bool) error {
@ -2578,8 +2580,8 @@ func (is *indexSearch) updateMetricIDsForOrSuffixWithFilter(prefix []byte, metri
ts := &is.ts
mp := &is.mp
mp.Reset()
maxLoops := len(sortedFilter) * maxIndexScanLoopsPerMetric
loops := 0
maxLoopsCount := uint64(len(sortedFilter)) * maxIndexScanLoopsPerMetric
var loopsCount uint64
loopsPaceLimiter := 0
ts.Seek(prefix)
var sf []uint64
@ -2610,8 +2612,8 @@ func (is *indexSearch) updateMetricIDsForOrSuffixWithFilter(prefix []byte, metri
return nil
}
sf = sortedFilter
loops += mp.MetricIDsLen()
if loops > maxLoops {
loopsCount += uint64(mp.MetricIDsLen())
if loopsCount > maxLoopsCount {
return errFallbackToMetricNameMatch
}
mp.ParseMetricIDs()
@ -2781,31 +2783,33 @@ func (is *indexSearch) tryUpdatingMetricIDsForDateRange(metricIDs *uint64set.Set
}
func (is *indexSearch) getMetricIDsForDateAndFilters(date uint64, tfs *TagFilters, maxMetrics int) (*uint64set.Set, error) {
// Sort tfs by the duration from previous queries.
// Sort tfs by loopsCount needed for performing each filter.
// This stats is usually collected from the previous queries.
// This way we limit the amount of work below by applying fast filters at first.
type tagFilterWithWeight struct {
tf *tagFilter
durationSeconds float64
loopsCount uint64
lastQueryTimestamp uint64
}
tfws := make([]tagFilterWithWeight, len(tfs.tfs))
currentTime := fasttime.UnixTimestamp()
for i := range tfs.tfs {
tf := &tfs.tfs[i]
durationSeconds, lastQueryTimestamp := is.getDurationAndTimestampForDateFilter(date, tf)
if durationSeconds == 0 {
// Assume that unknown tag filters can take quite big amounts of time.
durationSeconds = 1.0
loopsCount, lastQueryTimestamp := is.getLoopsCountAndTimestampForDateFilter(date, tf)
if currentTime > lastQueryTimestamp+60*60 {
// Reset loopsCount to 0 every hour for collecting updated stats for the tf.
loopsCount = 0
}
tfws[i] = tagFilterWithWeight{
tf: tf,
durationSeconds: durationSeconds,
loopsCount: loopsCount,
lastQueryTimestamp: lastQueryTimestamp,
}
}
sort.Slice(tfws, func(i, j int) bool {
a, b := &tfws[i], &tfws[j]
if a.durationSeconds != b.durationSeconds {
return a.durationSeconds < b.durationSeconds
if a.loopsCount != b.loopsCount {
return a.loopsCount < b.loopsCount
}
return a.tf.Less(b.tf)
})
@ -2872,7 +2876,7 @@ func (is *indexSearch) getMetricIDsForDateAndFilters(date uint64, tfs *TagFilter
// Short circuit - there is no need in applying the remaining filters to an empty set.
break
}
if float64(metricIDsLen)/metricNameMatchesPerSecond < tfw.durationSeconds {
if uint64(metricIDsLen)*maxIndexScanLoopsPerMetric < tfw.loopsCount {
// It should be faster performing metricName match on the remaining filters
// instead of scanning big number of entries in the inverted index for these filters.
tfsPostponed = append(tfsPostponed, tf)
@ -2908,12 +2912,6 @@ func (is *indexSearch) getMetricIDsForDateAndFilters(date uint64, tfs *TagFilter
return metricIDs, nil
}
// The estimated number of per-second loops inside updateMetricIDsByMetricNameMatch
//
// This value is used for determining when matching by metric name must be perfromed instead of matching
// by the remaining tag filters.
const metricNameMatchesPerSecond = 50000
func (is *indexSearch) storeDateMetricID(date, metricID uint64) error {
ii := getIndexItems()
defer putIndexItems(ii)
@ -3073,8 +3071,7 @@ func (is *indexSearch) getMetricIDsForDateTagFilter(tf *tagFilter, lastQueryTime
tfNew := *tf
tfNew.isNegative = false // isNegative for the original tf is handled by the caller.
tfNew.prefix = kb.B
startTime := time.Now()
metricIDs, err := is.getMetricIDsForTagFilter(&tfNew, filter, maxMetrics)
metricIDs, loopsCount, err := is.getMetricIDsForTagFilter(&tfNew, filter, maxMetrics)
kbPool.Put(kb)
currentTimestamp := fasttime.UnixTimestamp()
if currentTimestamp > lastQueryTimestamp+5 {
@ -3082,23 +3079,22 @@ func (is *indexSearch) getMetricIDsForDateTagFilter(tf *tagFilter, lastQueryTime
// Do not update it too frequently.
return metricIDs, err
}
// Store the duration for tag filter execution in the cache in order to sort tag filters
// Store the loopsCount for tag filter in the cache in order to sort tag filters
// in ascending durations on the next search.
durationSeconds := time.Since(startTime).Seconds()
if err != nil && durationSeconds < 10 {
// Set high duration for failing filter, so it is moved to the end of filter list.
durationSeconds = 10
if err != nil {
// Set high loopsCount for failing filter, so it is moved to the end of filter list.
loopsCount = 1 << 30
}
if metricIDs.Len() >= maxMetrics {
// Increase the duration for tag filter matching too many metrics,
// So next time it will be applied after filters matching lower number of metrics.
durationSeconds *= 2
// Increase loopsCount for tag filter matching too many metrics,
// So next time it is moved to the end of filter list.
loopsCount *= 2
}
is.storeDurationAndTimestampForDateFilter(date, tf, durationSeconds, currentTimestamp)
is.storeLoopsCountAndTimestampForDateFilter(date, tf, loopsCount, currentTimestamp)
return metricIDs, err
}
func (is *indexSearch) getDurationAndTimestampForDateFilter(date uint64, tf *tagFilter) (float64, uint64) {
func (is *indexSearch) getLoopsCountAndTimestampForDateFilter(date uint64, tf *tagFilter) (uint64, uint64) {
is.kb.B = appendDateTagFilterCacheKey(is.kb.B[:0], date, tf)
kb := kbPool.Get()
defer kbPool.Put(kb)
@ -3106,17 +3102,15 @@ func (is *indexSearch) getDurationAndTimestampForDateFilter(date uint64, tf *tag
if len(kb.B) != 16 {
return 0, 0
}
n := encoding.UnmarshalUint64(kb.B)
durationSeconds := math.Float64frombits(n)
loopsCount := encoding.UnmarshalUint64(kb.B)
timestamp := encoding.UnmarshalUint64(kb.B[8:])
return durationSeconds, timestamp
return loopsCount, timestamp
}
func (is *indexSearch) storeDurationAndTimestampForDateFilter(date uint64, tf *tagFilter, durationSeconds float64, timestamp uint64) {
func (is *indexSearch) storeLoopsCountAndTimestampForDateFilter(date uint64, tf *tagFilter, loopsCount, timestamp uint64) {
is.kb.B = appendDateTagFilterCacheKey(is.kb.B[:0], date, tf)
n := math.Float64bits(durationSeconds)
kb := kbPool.Get()
kb.B = encoding.MarshalUint64(kb.B[:0], n)
kb.B = encoding.MarshalUint64(kb.B[:0], loopsCount)
kb.B = encoding.MarshalUint64(kb.B, timestamp)
is.db.durationsPerDateTagFilterCache.Set(is.kb.B, kb.B)
kbPool.Put(kb)
@ -3243,8 +3237,8 @@ func (is *indexSearch) intersectMetricIDsWithTagFilterNocache(tf *tagFilter, fil
}
// Slow path - scan for all the rows with the given prefix.
maxLoops := filter.Len() * maxIndexScanSlowLoopsPerMetric
err := is.getMetricIDsForTagFilterSlow(tf, filter, maxLoops, func(metricID uint64) {
maxLoopsCount := uint64(filter.Len()) * maxIndexScanSlowLoopsPerMetric
_, err := is.getMetricIDsForTagFilterSlow(tf, filter, maxLoopsCount, func(metricID uint64) {
if tf.isNegative {
// filter must be equal to metricIDs
metricIDs.Del(metricID)

2
lib/storage/table.go
View File

@ -203,7 +203,7 @@ func (tb *table) MustClose() {
if n := atomic.LoadUint64(&ptw.refCount); n != 1 {
logger.Panicf("BUG: unexpected refCount=%d when closing the partition; probably there are pending searches", n)
}
ptw.pt.MustClose()
ptw.decRef()
}
// Release exclusive lock on the table.

4
lib/storage/tag_filters.go
View File

@ -221,7 +221,9 @@ type tagFilter struct {
value []byte
isNegative bool
isRegexp bool
matchCost uint64
// matchCost is a cost for matching a filter against a single string.
matchCost uint64
// Prefix always contains {nsPrefixTagToMetricIDs, key}.
// Additionally it contains: