Merge pull request #104 from grafana/56quarters/upstream-update

Upgrade prometheus to latest main

Author: pstibrany

RELEASE.md

@@ -37,7 +37,9 @@ Release cadence of first pre-releases being cut is 6 weeks.
 | v2.30          | 2021-09-08                                 | Ganesh Vernekar (GitHub: @codesome)         |
 | v2.31          | 2021-10-20                                 | Julien Pivotto (GitHub: @roidelapluie)      |
 | v2.32          | 2021-12-01                                 | Julius Volz (GitHub: @juliusv)              |
-| v2.33          | 2022-01-12                                 | **searching for volunteer**                 |
+| v2.33          | 2022-01-12                                 | Björn Rabenstein (GitHub: @beorn7)          |
+| v2.34          | 2022-02-23                                 | Chris Marchbanks (GitHub: @csmarchbanks)    |
+| v2.35          | 2022-04-06                                 | **searching for volunteer**                 |
 
 If you are interested in volunteering please create a pull request against the [prometheus/prometheus](https://github.com/prometheus/prometheus) repository and propose yourself for the release series of your choice.
 
@@ -70,7 +72,7 @@ If a bug fix got accidentally merged into main after non-bug-fix changes in main
 
 Maintaining the release branches for older minor releases happens on a best effort basis.
 
-### 0. Updating dependencies
+### 0. Updating dependencies and promoting/demoting experimental features
 
 A few days before a major or minor release, consider updating the dependencies.
 
@@ -85,6 +87,10 @@ you can skip the dependency update or only update select dependencies. In such a
 case, you have to create an issue or pull request in the GitHub project for
 later follow-up.
 
+This is also a good time to consider any experimental features and feature
+flags for promotion to stable or for deprecation or ultimately removal. Do any
+of these in pull requests, one per feature.
+
 #### Updating Go dependencies
 
 ```
@@ -155,3 +161,5 @@ For release candidate versions (`v2.16.0-rc.0`), run the benchmark for 3 days us
 If the release has happened in the latest release branch, merge the changes into main.
 
 Once the binaries have been uploaded, announce the release on `prometheus-announce@googlegroups.com`. (Please do not use `prometheus-users@googlegroups.com` for announcements anymore.) Check out previous announcement mails for inspiration.
+
+Finally, in case there is no release shepherd listed for the next release yet, find a volunteer.

discovery/legacymanager/manager_test.go

@@ -668,13 +668,16 @@ func TestTargetUpdatesOrder(t *testing.T) {
 			discoveryManager.updatert = 100 * time.Millisecond
 
 			var totalUpdatesCount int
-			provUpdates := make(chan []*targetgroup.Group)
 			for _, up := range tc.updates {
-				go newMockDiscoveryProvider(up...).Run(ctx, provUpdates)
 				if len(up) > 0 {
 					totalUpdatesCount += len(up)
 				}
 			}
+			provUpdates := make(chan []*targetgroup.Group, totalUpdatesCount)
+
+			for _, up := range tc.updates {
+				go newMockDiscoveryProvider(up...).Run(ctx, provUpdates)
+			}
 
 			for x := 0; x < totalUpdatesCount; x++ {
 				select {

discovery/manager_test.go

@@ -668,13 +668,16 @@ func TestTargetUpdatesOrder(t *testing.T) {
 			discoveryManager.updatert = 100 * time.Millisecond
 
 			var totalUpdatesCount int
-			provUpdates := make(chan []*targetgroup.Group)
 			for _, up := range tc.updates {
-				go newMockDiscoveryProvider(up...).Run(ctx, provUpdates)
 				if len(up) > 0 {
 					totalUpdatesCount += len(up)
 				}
 			}
+			provUpdates := make(chan []*targetgroup.Group, totalUpdatesCount)
+
+			for _, up := range tc.updates {
+				go newMockDiscoveryProvider(up...).Run(ctx, provUpdates)
+			}
 
 			for x := 0; x < totalUpdatesCount; x++ {
 				select {

go.mod

@@ -3,13 +3,13 @@ module github.com/prometheus/prometheus
 go 1.16
 
 require (
-	github.com/Azure/azure-sdk-for-go v60.3.0+incompatible
+	github.com/Azure/azure-sdk-for-go v61.1.0+incompatible
 	github.com/Azure/go-autorest/autorest v0.11.23
 	github.com/Azure/go-autorest/autorest/adal v0.9.18
 	github.com/Azure/go-autorest/autorest/to v0.4.0 // indirect
 	github.com/Azure/go-autorest/autorest/validation v0.3.1 // indirect
-	github.com/alecthomas/units v0.0.0-20210927113745-59d0afb8317a
-	github.com/aws/aws-sdk-go v1.42.25
+	github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137
+	github.com/aws/aws-sdk-go v1.42.28
 	github.com/cespare/xxhash/v2 v2.1.2
 	github.com/containerd/containerd v1.5.7 // indirect
 	github.com/dennwc/varint v1.0.0
@@ -27,7 +27,7 @@ require (
 	github.com/go-zookeeper/zk v1.0.2
 	github.com/gogo/protobuf v1.3.2
 	github.com/golang/snappy v0.0.4
-	github.com/google/pprof v0.0.0-20211122183932-1daafda22083
+	github.com/google/pprof v0.0.0-20211214055906-6f57359322fd
 	github.com/gophercloud/gophercloud v0.24.0
 	github.com/grpc-ecosystem/grpc-gateway v1.16.0
 	github.com/hashicorp/consul/api v1.12.0
@@ -59,14 +59,14 @@ require (
 	github.com/uber/jaeger-lib v2.4.1+incompatible
 	go.uber.org/atomic v1.9.0
 	go.uber.org/goleak v1.1.12
-	golang.org/x/net v0.0.0-20211209124913-491a49abca63
+	golang.org/x/net v0.0.0-20220105145211-5b0dc2dfae98
 	golang.org/x/oauth2 v0.0.0-20211104180415-d3ed0bb246c8
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
 	golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e
 	golang.org/x/time v0.0.0-20211116232009-f0f3c7e86c11
 	golang.org/x/tools v0.1.8
 	google.golang.org/api v0.63.0
-	google.golang.org/genproto v0.0.0-20211208223120-3a66f561d7aa
+	google.golang.org/genproto v0.0.0-20211223182754-3ac035c7e7cb
 	google.golang.org/protobuf v1.27.1
 	gopkg.in/alecthomas/kingpin.v2 v2.2.6
 	gopkg.in/yaml.v2 v2.4.0
@@ -75,7 +75,7 @@ require (
 	k8s.io/apimachinery v0.22.4
 	k8s.io/client-go v0.22.4
 	k8s.io/klog v1.0.0
-	k8s.io/klog/v2 v2.30.0
+	k8s.io/klog/v2 v2.40.1
 )
 
 replace (

go.sum

@@ -52,8 +52,8 @@ collectd.org v0.3.0/go.mod h1:A/8DzQBkF6abtvrT2j/AU/4tiBgJWYyh0y/oB/4MlWE=
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
 github.com/Azure/azure-sdk-for-go v16.2.1+incompatible/go.mod h1:9XXNKU+eRnpl9moKnB4QOLf1HestfXbmab5FXxiDBjc=
 github.com/Azure/azure-sdk-for-go v41.3.0+incompatible/go.mod h1:9XXNKU+eRnpl9moKnB4QOLf1HestfXbmab5FXxiDBjc=
-github.com/Azure/azure-sdk-for-go v60.3.0+incompatible h1:u6EXgnASaUOh38GXCwEpRs+u2bbfJpJpXeB42kU2cjg=
-github.com/Azure/azure-sdk-for-go v60.3.0+incompatible/go.mod h1:9XXNKU+eRnpl9moKnB4QOLf1HestfXbmab5FXxiDBjc=
+github.com/Azure/azure-sdk-for-go v61.1.0+incompatible h1:Qbz3jdfkXIPjZECEuk2E7i3iLhC9Ul74pG5mQRQC+z4=
+github.com/Azure/azure-sdk-for-go v61.1.0+incompatible/go.mod h1:9XXNKU+eRnpl9moKnB4QOLf1HestfXbmab5FXxiDBjc=
 github.com/Azure/go-ansiterm v0.0.0-20170929234023-d6e3b3328b78/go.mod h1:LmzpDX56iTiv29bbRTIsUNlaFfuhWRQBWjQdVyAevI8=
 github.com/Azure/go-ansiterm v0.0.0-20210617225240-d185dfc1b5a1 h1:UQHMgLO+TxOElx5B5HZ4hJQsoJ/PvUvKRhJHDQXO8P8=
 github.com/Azure/go-ansiterm v0.0.0-20210617225240-d185dfc1b5a1/go.mod h1:xomTg63KZ2rFqZQzSB4Vz2SUXa1BpHTVz9L5PTmPC4E=
@@ -154,8 +154,8 @@ github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRF
 github.com/alecthomas/units v0.0.0-20190717042225-c3de453c63f4/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d/go.mod h1:rBZYJk541a8SKzHPHnH3zbiI+7dagKZ0cgpgrD7Fyho=
 github.com/alecthomas/units v0.0.0-20210208195552-ff826a37aa15/go.mod h1:OMCwj8VM1Kc9e19TLln2VL61YJF0x1XFtfdL4JdbSyE=
-github.com/alecthomas/units v0.0.0-20210927113745-59d0afb8317a h1:E/8AP5dFtMhl5KPJz66Kt9G0n+7Sn41Fy1wv9/jHOrc=
-github.com/alecthomas/units v0.0.0-20210927113745-59d0afb8317a/go.mod h1:OMCwj8VM1Kc9e19TLln2VL61YJF0x1XFtfdL4JdbSyE=
+github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137 h1:s6gZFSlWYmbqAuRjVTiNNhvNRfY2Wxp9nhfyel4rklc=
+github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137/go.mod h1:OMCwj8VM1Kc9e19TLln2VL61YJF0x1XFtfdL4JdbSyE=
 github.com/alexflint/go-filemutex v0.0.0-20171022225611-72bdc8eae2ae/go.mod h1:CgnQgUtFrFz9mxFNtED3jI5tLDjKlOM+oUF/sTk6ps0=
 github.com/andreyvit/diff v0.0.0-20170406064948-c7f18ee00883/go.mod h1:rCTlJbsFo29Kk6CurOXKm700vrz8f0KW0JNfpkRJY/8=
 github.com/antihax/optional v0.0.0-20180407024304-ca021399b1a6/go.mod h1:V8iCPQYkqmusNa815XgQio277wI47sdRh1dUOLdyC6Q=
@@ -188,8 +188,8 @@ github.com/aws/aws-sdk-go v1.30.12/go.mod h1:5zCpMtNQVjRREroY7sYe8lOMRSxkhG6MZve
 github.com/aws/aws-sdk-go v1.34.28/go.mod h1:H7NKnBqNVzoTJpGfLrQkkD+ytBA93eiDYi/+8rV9s48=
 github.com/aws/aws-sdk-go v1.38.35/go.mod h1:hcU610XS61/+aQV88ixoOzUoG7v3b31pl2zKMmprdro=
 github.com/aws/aws-sdk-go v1.40.11/go.mod h1:585smgzpB/KqRA+K3y/NL/oYRqQvpNJYvLm+LY1U59Q=
-github.com/aws/aws-sdk-go v1.42.25 h1:BbdvHAi+t9LRiaYUyd53noq9jcaAcfzOhSVbKfr6Avs=
-github.com/aws/aws-sdk-go v1.42.25/go.mod h1:gyRszuZ/icHmHAVE4gc/r+cfCmhA1AD+vqfWbgI+eHs=
+github.com/aws/aws-sdk-go v1.42.28 h1:YJtgL7IGSN41saY4JLW08jya5nU0vGcuAeAa1OL2M6c=
+github.com/aws/aws-sdk-go v1.42.28/go.mod h1:OGr6lGMAKGlG9CVrYnWYDKIyb829c6EVBRjxqjmPepc=
 github.com/aws/aws-sdk-go-v2 v0.18.0/go.mod h1:JWVYvqSMppoMJC0x5wdwiImzgXTI9FuZwxzkQq9wy+g=
 github.com/benbjohnson/immutable v0.2.1/go.mod h1:uc6OHo6PN2++n98KHLxW8ef4W42ylHiQSENghE1ezxI=
 github.com/benbjohnson/tmpl v1.0.0/go.mod h1:igT620JFIi44B6awvU9IsDhR77IXWtFigTLil/RPdps=
@@ -719,8 +719,8 @@ github.com/google/pprof v0.0.0-20210226084205-cbba55b83ad5/go.mod h1:kpwsk12EmLe
 github.com/google/pprof v0.0.0-20210601050228-01bbb1931b22/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
 github.com/google/pprof v0.0.0-20210609004039-a478d1d731e9/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
 github.com/google/pprof v0.0.0-20210720184732-4bb14d4b1be1/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
-github.com/google/pprof v0.0.0-20211122183932-1daafda22083 h1:c8EUapQFi+kjzedr4c6WqbwMdmB95+oDBWZ5XFHFYxY=
-github.com/google/pprof v0.0.0-20211122183932-1daafda22083/go.mod h1:KgnwoLYCZ8IQu3XUZ8Nc/bM9CCZFOyjUNOSygVozoDg=
+github.com/google/pprof v0.0.0-20211214055906-6f57359322fd h1:1FjCyPC+syAzJ5/2S8fqdZK1R22vvA0J7JZKcuOIQ7Y=
+github.com/google/pprof v0.0.0-20211214055906-6f57359322fd/go.mod h1:KgnwoLYCZ8IQu3XUZ8Nc/bM9CCZFOyjUNOSygVozoDg=
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
 github.com/google/uuid v1.0.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/google/uuid v1.1.1/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
@@ -1534,8 +1534,9 @@ golang.org/x/net v0.0.0-20210726213435-c6fcb2dbf985/go.mod h1:9nx3DQGgdP8bBQD5qx
 golang.org/x/net v0.0.0-20210813160813-60bc85c4be6d/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20211015210444-4f30a5c0130f/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-golang.org/x/net v0.0.0-20211209124913-491a49abca63 h1:iocB37TsdFuN6IBRZ+ry36wrkoV51/tl5vOWqkcPGvY=
-golang.org/x/net v0.0.0-20211209124913-491a49abca63/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20211216030914-fe4d6282115f/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20220105145211-5b0dc2dfae98 h1:+6WJMRLHlD7X7frgp7TUZ36RnQzSf9wVVTNakEp+nqY=
+golang.org/x/net v0.0.0-20220105145211-5b0dc2dfae98/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
@@ -1906,8 +1907,9 @@ google.golang.org/genproto v0.0.0-20210909211513-a8c4777a87af/go.mod h1:eFjDcFEc
 google.golang.org/genproto v0.0.0-20210924002016-3dee208752a0/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
 google.golang.org/genproto v0.0.0-20211118181313-81c1377c94b1/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
 google.golang.org/genproto v0.0.0-20211206160659-862468c7d6e0/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
-google.golang.org/genproto v0.0.0-20211208223120-3a66f561d7aa h1:I0YcKz0I7OAhddo7ya8kMnvprhcWM045PmkBdMO9zN0=
 google.golang.org/genproto v0.0.0-20211208223120-3a66f561d7aa/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
+google.golang.org/genproto v0.0.0-20211223182754-3ac035c7e7cb h1:ZrsicilzPCS/Xr8qtBZZLpy4P9TYXAfl49ctG1/5tgw=
+google.golang.org/genproto v0.0.0-20211223182754-3ac035c7e7cb/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
 google.golang.org/grpc v0.0.0-20160317175043-d3ddb4469d5a/go.mod h1:yo6s7OP7yaDglbqo1J04qKzAhqBH6lvTonzMVmEdcZw=
 google.golang.org/grpc v1.17.0/go.mod h1:6QZJwpn2B+Zp71q/5VxRsJ6NXXVCE5NRUHRo+f3cWCs=
 google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=

storage/remote/queue_manager.go

@@ -15,6 +15,7 @@ package remote
 
 import (
 	"context"
+	"errors"
 	"math"
 	"strconv"
 	"sync"
@@ -1311,12 +1312,16 @@ func (s *shards) sendSamplesWithBackoff(ctx context.Context, samples []prompb.Ti
 	}
 
 	err = sendWriteRequestWithBackoff(ctx, s.qm.cfg, s.qm.logger, attemptStore, onRetry)
-	if err != nil {
+	if errors.Is(err, context.Canceled) {
+		// When there is resharding, we cancel the context for this queue, which means the data is not sent.
+		// So we exit early to not update the metrics.
 		return err
 	}
+
 	s.qm.metrics.sentBytesTotal.Add(float64(reqSize))
 	s.qm.metrics.highestSentTimestamp.Set(float64(highest / 1000))
-	return nil
+
+	return err
 }
 
 func sendWriteRequestWithBackoff(ctx context.Context, cfg config.QueueConfig, l log.Logger, attempt func(int) error, onRetry func()) error {

tsdb/exemplar.go

@@ -27,8 +27,12 @@ import (
 	"github.com/prometheus/prometheus/storage"
 )
 
-// Indicates that there is no index entry for an exmplar.
-const noExemplar = -1
+const (
+	// Indicates that there is no index entry for an exmplar.
+	noExemplar = -1
+	// Estimated number of exemplars per series, for sizing the index.
+	estimatedExemplarsPerSeries = 16
+)
 
 type CircularExemplarStorage struct {
 	lock      sync.RWMutex
@@ -117,7 +121,7 @@ func NewCircularExemplarStorage(len int64, m *ExemplarMetrics) (ExemplarStorage,
 	}
 	c := &CircularExemplarStorage{
 		exemplars: make([]*circularBufferEntry, len),
-		index:     make(map[string]*indexEntry),
+		index:     make(map[string]*indexEntry, len/estimatedExemplarsPerSeries),
 		metrics:   m,
 	}
 
@@ -202,7 +206,8 @@ Outer:
 }
 
 func (ce *CircularExemplarStorage) ValidateExemplar(l labels.Labels, e exemplar.Exemplar) error {
-	seriesLabels := l.String()
+	var buf [1024]byte
+	seriesLabels := l.Bytes(buf[:])
 
 	// TODO(bwplotka): This lock can lock all scrapers, there might high contention on this on scale.
 	// Optimize by moving the lock to be per series (& benchmark it).
@@ -213,7 +218,7 @@ func (ce *CircularExemplarStorage) ValidateExemplar(l labels.Labels, e exemplar.
 
 // Not thread safe. The append parameters tells us whether this is an external validation, or internal
 // as a result of an AddExemplar call, in which case we should update any relevant metrics.
-func (ce *CircularExemplarStorage) validateExemplar(l string, e exemplar.Exemplar, append bool) error {
+func (ce *CircularExemplarStorage) validateExemplar(key []byte, e exemplar.Exemplar, append bool) error {
 	if len(ce.exemplars) <= 0 {
 		return storage.ErrExemplarsDisabled
 	}
@@ -230,7 +235,7 @@ func (ce *CircularExemplarStorage) validateExemplar(l string, e exemplar.Exempla
 		}
 	}
 
-	idx, ok := ce.index[l]
+	idx, ok := ce.index[string(key)]
 	if !ok {
 		return nil
 	}
@@ -269,7 +274,7 @@ func (ce *CircularExemplarStorage) Resize(l int64) int {
 	oldNextIndex := int64(ce.nextIndex)
 
 	ce.exemplars = make([]*circularBufferEntry, l)
-	ce.index = make(map[string]*indexEntry)
+	ce.index = make(map[string]*indexEntry, l/estimatedExemplarsPerSeries)
 	ce.nextIndex = 0
 
 	// Replay as many entries as needed, starting with oldest first.
@@ -305,13 +310,14 @@ func (ce *CircularExemplarStorage) Resize(l int64) int {
 // migrate is like AddExemplar but reuses existing structs. Expected to be called in batch and requires
 // external lock and does not compute metrics.
 func (ce *CircularExemplarStorage) migrate(entry *circularBufferEntry) {
-	seriesLabels := entry.ref.seriesLabels.String()
+	var buf [1024]byte
+	seriesLabels := entry.ref.seriesLabels.Bytes(buf[:])
 
-	idx, ok := ce.index[seriesLabels]
+	idx, ok := ce.index[string(seriesLabels)]
 	if !ok {
 		idx = entry.ref
 		idx.oldest = ce.nextIndex
-		ce.index[seriesLabels] = idx
+		ce.index[string(seriesLabels)] = idx
 	} else {
 		entry.ref = idx
 		ce.exemplars[idx.newest].next = ce.nextIndex
@@ -329,7 +335,8 @@ func (ce *CircularExemplarStorage) AddExemplar(l labels.Labels, e exemplar.Exemp
 		return storage.ErrExemplarsDisabled
 	}
 
-	seriesLabels := l.String()
+	var buf [1024]byte
+	seriesLabels := l.Bytes(buf[:])
 
 	// TODO(bwplotka): This lock can lock all scrapers, there might high contention on this on scale.
 	// Optimize by moving the lock to be per series (& benchmark it).
@@ -345,33 +352,34 @@ func (ce *CircularExemplarStorage) AddExemplar(l labels.Labels, e exemplar.Exemp
 		return err
 	}
 
-	_, ok := ce.index[seriesLabels]
+	_, ok := ce.index[string(seriesLabels)]
 	if !ok {
-		ce.index[seriesLabels] = &indexEntry{oldest: ce.nextIndex, seriesLabels: l}
+		ce.index[string(seriesLabels)] = &indexEntry{oldest: ce.nextIndex, seriesLabels: l}
 	} else {
-		ce.exemplars[ce.index[seriesLabels].newest].next = ce.nextIndex
+		ce.exemplars[ce.index[string(seriesLabels)].newest].next = ce.nextIndex
 	}
 
 	if prev := ce.exemplars[ce.nextIndex]; prev == nil {
 		ce.exemplars[ce.nextIndex] = &circularBufferEntry{}
 	} else {
 		// There exists exemplar already on this ce.nextIndex entry, drop it, to make place
 		// for others.
-		prevLabels := prev.ref.seriesLabels.String()
+		var buf [1024]byte
+		prevLabels := prev.ref.seriesLabels.Bytes(buf[:])
 		if prev.next == noExemplar {
 			// Last item for this series, remove index entry.
-			delete(ce.index, prevLabels)
+			delete(ce.index, string(prevLabels))
 		} else {
-			ce.index[prevLabels].oldest = prev.next
+			ce.index[string(prevLabels)].oldest = prev.next
 		}
 	}
 
 	// Default the next value to -1 (which we use to detect that we've iterated through all exemplars for a series in Select)
 	// since this is the first exemplar stored for this series.
 	ce.exemplars[ce.nextIndex].next = noExemplar
 	ce.exemplars[ce.nextIndex].exemplar = e
-	ce.exemplars[ce.nextIndex].ref = ce.index[seriesLabels]
-	ce.index[seriesLabels].newest = ce.nextIndex
+	ce.exemplars[ce.nextIndex].ref = ce.index[string(seriesLabels)]
+	ce.index[string(seriesLabels)].newest = ce.nextIndex
 
 	ce.nextIndex = (ce.nextIndex + 1) % len(ce.exemplars)