fix: Fixes pattern pruning stability (#13429)

pkg/pattern/ingester_querier.go

@@ -5,23 +5,27 @@ import (
 	"errors"
 	"math"
 	"net/http"
+	"sort"
 
 	"github.com/go-kit/log"
 	"github.com/go-kit/log/level"
 	"github.com/grafana/dskit/httpgrpc"
 	"github.com/grafana/dskit/ring"
 	"github.com/prometheus/client_golang/prometheus"
+	"golang.org/x/sync/errgroup"
 
 	"github.com/grafana/loki/v3/pkg/logproto"
 	"github.com/grafana/loki/v3/pkg/logql/syntax"
-	"github.com/grafana/loki/v3/pkg/pattern/drain"
 
 	loki_iter "github.com/grafana/loki/v3/pkg/iter"
 	pattern_iter "github.com/grafana/loki/v3/pkg/pattern/iter"
 )
 
 // TODO(kolesnikovae): parametrise QueryPatternsRequest
-const minClusterSize = 30
+const (
+	minClusterSize = 30
+	maxPatterns    = 300
+)
 
 var ErrParseQuery = errors.New("only byte_over_time and count_over_time queries without filters are supported")
 
@@ -132,36 +136,63 @@ func (q *IngesterQuerier) querySample(ctx context.Context, req *logproto.QuerySa
 	return iterators, nil
 }
 
-func prunePatterns(resp *logproto.QueryPatternsResponse, minClusterSize int, metrics *ingesterQuerierMetrics) *logproto.QueryPatternsResponse {
-	pruneConfig := drain.DefaultConfig()
-	pruneConfig.SimTh = 1.0 // Merge & de-dup patterns but don't modify them
-
+func prunePatterns(resp *logproto.QueryPatternsResponse, minClusterSize int64, metrics *ingesterQuerierMetrics) *logproto.QueryPatternsResponse {
 	patternsBefore := len(resp.Series)
-	d := drain.New(pruneConfig, "", nil)
-	for _, p := range resp.Series {
-		d.TrainPattern(p.GetPattern(), p.Samples)
+	total := make([]int64, len(resp.Series))
+
+	for i, p := range resp.Series {
+		for _, s := range p.Samples {
+			total[i] += s.Value
+		}
 	}
 
-	resp.Series = resp.Series[:0]
-	for _, cluster := range d.Clusters() {
-		if cluster.Size < minClusterSize {
-			continue
+	// Create a slice of structs to keep Series and total together
+	type SeriesWithTotal struct {
+		Series *logproto.PatternSeries
+		Total  int64
+	}
+
+	seriesWithTotals := make([]SeriesWithTotal, len(resp.Series))
+	for i := range resp.Series {
+		seriesWithTotals[i] = SeriesWithTotal{
+			Series: resp.Series[i],
+			Total:  total[i],
 		}
-		pattern := d.PatternString(cluster)
-		if pattern == "" {
-			continue
+	}
+
+	// Sort the slice of structs by the Total field
+	sort.Slice(seriesWithTotals, func(i, j int) bool {
+		return seriesWithTotals[i].Total > seriesWithTotals[j].Total
+	})
+
+	// Initialize a variable to keep track of the position for valid series
+	pos := 0
+
+	// Iterate over the seriesWithTotals
+	for i := range seriesWithTotals {
+		if seriesWithTotals[i].Total >= minClusterSize {
+			// Place the valid series at the current position
+			resp.Series[pos] = seriesWithTotals[i].Series
+			pos++
 		}
-		resp.Series = append(resp.Series,
-			logproto.NewPatternSeries(pattern, cluster.Samples()))
 	}
+
+	// Slice the resp.Series to include only the valid series
+	resp.Series = resp.Series[:pos]
+
+	if len(resp.Series) > maxPatterns {
+		resp.Series = resp.Series[:maxPatterns]
+	}
+
 	metrics.patternsPrunedTotal.Add(float64(patternsBefore - len(resp.Series)))
 	metrics.patternsRetainedTotal.Add(float64(len(resp.Series)))
+
 	return resp
 }
 
 // ForAllIngesters runs f, in parallel, for all ingesters
 func (q *IngesterQuerier) forAllIngesters(ctx context.Context, f func(context.Context, logproto.PatternClient) (interface{}, error)) ([]ResponseFromIngesters, error) {
-	replicationSet, err := q.ringClient.Ring().GetReplicationSetForOperation(ring.Read)
+	replicationSet, err := q.ringClient.Ring().GetAllHealthy(ring.Read)
 	if err != nil {
 		return nil, err
 	}
@@ -174,32 +205,29 @@ type ResponseFromIngesters struct {
 	response interface{}
 }
 
-// forGivenIngesters runs f, in parallel, for given ingesters
 func (q *IngesterQuerier) forGivenIngesters(ctx context.Context, replicationSet ring.ReplicationSet, f func(context.Context, logproto.PatternClient) (interface{}, error)) ([]ResponseFromIngesters, error) {
-	cfg := ring.DoUntilQuorumConfig{
-		// Nothing here
-	}
-	results, err := ring.DoUntilQuorum(ctx, replicationSet, cfg, func(ctx context.Context, ingester *ring.InstanceDesc) (ResponseFromIngesters, error) {
-		client, err := q.ringClient.Pool().GetClientFor(ingester.Addr)
-		if err != nil {
-			return ResponseFromIngesters{addr: ingester.Addr}, err
-		}
-
-		resp, err := f(ctx, client.(logproto.PatternClient))
-		if err != nil {
-			return ResponseFromIngesters{addr: ingester.Addr}, err
-		}
-
-		return ResponseFromIngesters{ingester.Addr, resp}, nil
-	}, func(ResponseFromIngesters) {
-		// Nothing to do
-	})
-	if err != nil {
+	g, ctx := errgroup.WithContext(ctx)
+	responses := make([]ResponseFromIngesters, len(replicationSet.Instances))
+
+	for i, ingester := range replicationSet.Instances {
+		ingester := ingester
+		i := i
+		g.Go(func() error {
+			client, err := q.ringClient.Pool().GetClientFor(ingester.Addr)
+			if err != nil {
+				return err
+			}
+
+			resp, err := f(ctx, client.(logproto.PatternClient))
+			if err != nil {
+				return err
+			}
+			responses[i] = ResponseFromIngesters{addr: ingester.Addr, response: resp}
+			return nil
+		})
+	}
+	if err := g.Wait(); err != nil {
 		return nil, err
 	}
-
-	responses := make([]ResponseFromIngesters, 0, len(results))
-	responses = append(responses, results...)
-
-	return responses, err
+	return responses, nil
 }