Head Cardinality Status Page (#6125)

* Adding TSDB Head Stats like cardinality to Status Page
Signed-off-by: NSharad Gaur <sgaur@splunk.com>

* Moving mutx to Head
Signed-off-by: NSharad Gaur <sgaur@splunk.com>

* Renaming variabls
Signed-off-by: NSharad Gaur <sgaur@splunk.com>

* Renaming variabls and html
Signed-off-by: NSharad Gaur <sgaur@splunk.com>

* Removing unwanted whitespaces
Signed-off-by: NSharad Gaur <sgaur@splunk.com>

* Adding Tests, Banchmarks and Max Heap for Postings Stats
Signed-off-by: NSharad Gaur <sgaur@splunk.com>

* Adding more tests for postingstats and web handler
Signed-off-by: NSharad Gaur <sgaur@splunk.com>

* Adding more tests for postingstats and web handler
Signed-off-by: NSharad Gaur <sgaur@splunk.com>

* Remove generated asset file that is no longer used
Signed-off-by: NChris Marchbanks <csmarchbanks@gmail.com>

* Changing comment and variable name for more readability
Signed-off-by: NSharad Gaur <sgaur@splunk.com>

* Using time.Duration in postings status function and removing refresh button from web page
Signed-off-by: NSharad Gaur <sgaur@splunk.com>

tsdb/head.go

@@ -87,6 +87,10 @@ type Head struct {
 	deleted    map[uint64]int // Deleted series, and what WAL segment they must be kept until.
 
 	postings *index.MemPostings // postings lists for terms
+
+	cardinalityMutex      sync.Mutex
+	cardinalityCache      *index.PostingsStats // posting stats cache which will expire after 30sec
+	lastPostingsStatsCall time.Duration        // last posting stats call (PostgingsCardinalityStats()) time for caching
 }
 
 type headMetrics struct {
@@ -231,6 +235,26 @@ func newHeadMetrics(h *Head, r prometheus.Registerer) *headMetrics {
 	return m
 }
 
+const cardinalityCacheExpirationTime = time.Duration(30) * time.Second
+
+// PostingsCardinalityStats returns top 10 highest cardinality stats By label and value names.
+func (h *Head) PostingsCardinalityStats(statsByLabelName string) *index.PostingsStats {
+	h.cardinalityMutex.Lock()
+	defer h.cardinalityMutex.Unlock()
+	currentTime := time.Duration(time.Now().Unix()) * time.Second
+	seconds := currentTime - h.lastPostingsStatsCall
+	if seconds > cardinalityCacheExpirationTime {
+		h.cardinalityCache = nil
+	}
+	if h.cardinalityCache != nil {
+		return h.cardinalityCache
+	}
+	h.cardinalityCache = h.postings.Stats(statsByLabelName)
+	h.lastPostingsStatsCall = time.Duration(time.Now().Unix()) * time.Second
+
+	return h.cardinalityCache
+}
+
 // NewHead opens the head block in dir.
 func NewHead(r prometheus.Registerer, l log.Logger, wal *wal.WAL, chunkRange int64) (*Head, error) {
 	if l == nil {

tsdb/index/postings.go

@@ -79,6 +79,57 @@ func (p *MemPostings) SortedKeys() []labels.Label {
 	return keys
 }
 
+// PostingsStats contains cardinality based statistics for postings.
+type PostingsStats struct {
+	CardinalityMetricsStats []Stat
+	CardinalityLabelStats   []Stat
+	LabelValueStats         []Stat
+	LabelValuePairsStats    []Stat
+}
+
+// Stats calculates the cardinality statistics from postings.
+func (p *MemPostings) Stats(label string) *PostingsStats {
+	const maxNumOfRecords = 10
+	var size uint64
+
+	p.mtx.RLock()
+
+	metrics := &maxHeap{}
+	labels := &maxHeap{}
+	labelValueLenght := &maxHeap{}
+	labelValuePairs := &maxHeap{}
+
+	metrics.init(maxNumOfRecords)
+	labels.init(maxNumOfRecords)
+	labelValueLenght.init(maxNumOfRecords)
+	labelValuePairs.init(maxNumOfRecords)
+
+	for n, e := range p.m {
+		if n == "" {
+			continue
+		}
+		labels.push(Stat{Name: n, Count: uint64(len(e))})
+		size = 0
+		for name, values := range e {
+			if n == label {
+				metrics.push(Stat{Name: name, Count: uint64(len(values))})
+			}
+			labelValuePairs.push(Stat{Name: n + "=" + name, Count: uint64(len(values))})
+			size += uint64(len(name))
+		}
+		labelValueLenght.push(Stat{Name: n, Count: size})
+	}
+
+	p.mtx.RUnlock()
+
+	return &PostingsStats{
+		CardinalityMetricsStats: metrics.get(),
+		CardinalityLabelStats:   labels.get(),
+		LabelValueStats:         labelValueLenght.get(),
+		LabelValuePairsStats:    labelValuePairs.get(),
+	}
+}
+
 // Get returns a postings list for the given label pair.
 func (p *MemPostings) Get(name, value string) Postings {
 	var lp []uint64

tsdb/index/postings_test.go

@@ -814,6 +814,36 @@ func TestWithoutPostings(t *testing.T) {
 	}
 }
 
+func BenchmarkPostings_Stats(b *testing.B) {
+	p := NewMemPostings()
+
+	createPostingsLabelValues := func(name, valuePrefix string, count int) {
+		for n := 1; n < count; n++ {
+			value := fmt.Sprintf("%s-%d", valuePrefix, n)
+			p.Add(uint64(n), labels.FromStrings(name, value))
+		}
+
+	}
+	createPostingsLabelValues("__name__", "metrics_name_can_be_very_big_and_bad", 1e3)
+	for i := 0; i < 20; i++ {
+		createPostingsLabelValues(fmt.Sprintf("host-%d", i), "metrics_name_can_be_very_big_and_bad", 1e3)
+		createPostingsLabelValues(fmt.Sprintf("instance-%d", i), "10.0.IP.", 1e3)
+		createPostingsLabelValues(fmt.Sprintf("job-%d", i), "Small_Job_name", 1e3)
+		createPostingsLabelValues(fmt.Sprintf("err-%d", i), "avg_namespace-", 1e3)
+		createPostingsLabelValues(fmt.Sprintf("team-%d", i), "team-", 1e3)
+		createPostingsLabelValues(fmt.Sprintf("container_name-%d", i), "pod-", 1e3)
+		createPostingsLabelValues(fmt.Sprintf("cluster-%d", i), "newcluster-", 1e3)
+		createPostingsLabelValues(fmt.Sprintf("uid-%d", i), "123412312312312311-", 1e3)
+		createPostingsLabelValues(fmt.Sprintf("area-%d", i), "new_area_of_work-", 1e3)
+		createPostingsLabelValues(fmt.Sprintf("request_id-%d", i), "owner_name_work-", 1e3)
+	}
+	b.ResetTimer()
+	for n := 0; n < b.N; n++ {
+		p.Stats("__name__")
+	}
+
+}
+
 func TestMemPostings_Delete(t *testing.T) {
 	p := NewMemPostings()
 	p.Add(1, labels.FromStrings("lbl1", "a"))

tsdb/index/postingsstats.go

+// Copyright 2019 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package index
+
+import (
+	"math"
+	"sort"
+)
+
+// Stat holds values for a single cardinality statistic.
+type Stat struct {
+	Name  string
+	Count uint64
+}
+
+type maxHeap struct {
+	maxLength int
+	minValue  uint64
+	minIndex  int
+	Items     []Stat
+}
+
+func (m *maxHeap) init(len int) {
+	m.maxLength = len
+	m.minValue = math.MaxUint64
+	m.Items = make([]Stat, 0, len)
+}
+
+func (m *maxHeap) push(item Stat) {
+	if len(m.Items) < m.maxLength {
+		if item.Count < m.minValue {
+			m.minValue = item.Count
+			m.minIndex = len(m.Items)
+		}
+		m.Items = append(m.Items, item)
+		return
+	}
+	if item.Count < m.minValue {
+		return
+	}
+
+	m.Items[m.minIndex] = item
+	m.minValue = item.Count
+
+	for i, stat := range m.Items {
+		if stat.Count < m.minValue {
+			m.minValue = stat.Count
+			m.minIndex = i
+		}
+	}
+
+}
+
+func (m *maxHeap) get() []Stat {
+	sort.Slice(m.Items, func(i, j int) bool {
+		return m.Items[i].Count > m.Items[j].Count
+	})
+	return m.Items
+}

tsdb/index/postingsstats_test.go

+// Copyright 2019 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package index
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/prometheus/prometheus/util/testutil"
+)
+
+func TestPostingsStats(t *testing.T) {
+	stats := &maxHeap{}
+	max := 3000000
+	heapLength := 10
+	stats.init(heapLength)
+	for i := 0; i < max; i++ {
+		item := Stat{
+			Name:  "Label-da",
+			Count: uint64(i),
+		}
+		stats.push(item)
+	}
+	stats.push(Stat{Name: "Stuff", Count: 3000000})
+
+	data := stats.get()
+	testutil.Equals(t, 10, len(data))
+	for i := 0; i < heapLength; i++ {
+		fmt.Printf("%d", data[i].Count)
+		testutil.Equals(t, uint64(max-i), data[i].Count)
+	}
+
+}
+
+func TestPostingsStats2(t *testing.T) {
+	stats := &maxHeap{}
+	heapLength := 10
+
+	stats.init(heapLength)
+	stats.push(Stat{Name: "Stuff", Count: 10})
+	stats.push(Stat{Name: "Stuff", Count: 11})
+	stats.push(Stat{Name: "Stuff", Count: 1})
+	stats.push(Stat{Name: "Stuff", Count: 6})
+
+	data := stats.get()
+
+	testutil.Equals(t, 4, len(data))
+	testutil.Equals(t, uint64(11), data[0].Count)
+}
+func BenchmarkPostingStatsMaxHep(b *testing.B) {
+	stats := &maxHeap{}
+	max := 9000000
+	heapLength := 10
+	b.ResetTimer()
+	for n := 0; n < b.N; n++ {
+		stats.init(heapLength)
+		for i := 0; i < max; i++ {
+			item := Stat{
+				Name:  "Label-da",
+				Count: uint64(i),
+			}
+			stats.push(item)
+		}
+		stats.get()
+	}
+
+}

web/ui/templates/status.html

@@ -21,14 +21,6 @@
           <th>Last successful configuration reload</th>
           <td>{{.LastConfigTime.UTC}}</td>
         </tr>
-        <tr>
-          <th>Head chunks</th>
-          <td>{{.ChunkCount}}</td>
-        </tr>
-        <tr>
-          <th>Head time series</th>
-          <td>{{.TimeSeriesCount}}</td>
-        </tr>
         <tr>
           <th>WAL corruptions</th>
           <td>{{.CorruptionCount}}</td>
@@ -101,5 +93,83 @@
       </tbody>
     </table>
 
+    <h2 id="headstatus">Head Stats</h2>
+    <table class="table table-sm table-bordered table-striped table-hover">
+      <tbody>
+        <tr>
+           <th>Number Of Series </th>
+           <th>Number of Chunks</th>
+           <th>Current Max Time</th>
+           <th>Current Min Time</th>
+        </tr>
+        <tr>
+          <td scope="row">{{ .NumSeries}}</th>
+          <td>{{.ChunkCount}}</td>  
+          <td>{{ .MaxTime}}</td>
+          <td>{{ .MinTime}}</td>
+        </tr>
+      </tbody>
+    </table>
+    <div>Total Query Time: {{ .Duration }} Seconds</div>
+    <h3 id="headstatus">Highest Cardinality Labels </h3>
+    <table class="table table-sm table-bordered table-striped table-hover">
+      <tbody>
+        <tr>
+           <th>Name</th>
+           <th>Count</th>
+        </tr>
+        {{ range .Stats.CardinalityLabelStats }}
+        <tr>
+          <td scope="row">{{.Name}}</th>
+          <td>{{.Count}}</td>  
+        </tr>
+        {{end}}
+      </tbody>
+    </table>
+    <h3 id="headstatus">Highest Cardinality Metric Names</h3>
+    <table class="table table-sm table-bordered table-striped table-hover">
+        <tbody>
+          <tr>
+             <th>Name</th>
+             <th>Count</th>
+          </tr>
+          {{ range .Stats.CardinalityMetricsStats }}
+          <tr>
+            <td scope="row">{{.Name}}</th>
+            <td>{{.Count}}</td>  
+          </tr>
+          {{end}}
+        </tbody>
+      </table>
+      <h3 id="headstatus">Label Names With Highest Cumulative Label Value Length</h3>
+      <table class="table table-sm table-bordered table-striped table-hover">
+          <tbody>
+            <tr>
+               <th>Name</th>
+               <th>Length</th>
+            </tr>
+            {{ range .Stats.LabelValueStats }}
+            <tr>
+              <td scope="row">{{.Name}}</th>
+              <td>{{.Count}}</td>  
+            </tr>
+            {{end}}
+          </tbody>
+        </table>      
+        <h3 id="headstatus">Most Common Label Pairs</h3>
+        <table class="table table-sm table-bordered table-striped table-hover">
+            <tbody>
+              <tr>
+                 <th>Name</th>
+                 <th>Count</th>
+              </tr>
+              {{ range .Stats.LabelValuePairsStats }}
+              <tr>
+                <td scope="row">{{.Name}}</th>
+                <td>{{.Count}}</td>  
+              </tr>
+              {{end}}
+            </tbody>
+        </table>   
   </div>
 {{end}}

web/web.go

@@ -51,6 +51,7 @@ import (
 	"github.com/prometheus/common/route"
 	"github.com/prometheus/common/server"
 	"github.com/prometheus/prometheus/tsdb"
+	"github.com/prometheus/prometheus/tsdb/index"
 	"github.com/soheilhy/cmux"
 	"golang.org/x/net/netutil"
 	"google.golang.org/grpc"
@@ -715,6 +716,11 @@ func (h *Handler) status(w http.ResponseWriter, r *http.Request) {
 		LastConfigTime      time.Time
 		ReloadConfigSuccess bool
 		StorageRetention    string
+		NumSeries           uint64
+		MaxTime             int64
+		MinTime             int64
+		Stats               *index.PostingsStats
+		Duration            string
 	}{
 		Birth:          h.birth,
 		CWD:            h.cwd,
@@ -755,6 +761,14 @@ func (h *Handler) status(w http.ResponseWriter, r *http.Request) {
 			status.LastConfigTime = time.Unix(int64(toFloat64(mF)), 0)
 		}
 	}
+	db := h.tsdb()
+	startTime := time.Now().UnixNano()
+	status.Stats = db.Head().PostingsCardinalityStats("__name__")
+	status.Duration = fmt.Sprintf("%.3f", float64(time.Now().UnixNano()-startTime)/float64(1e9))
+	status.NumSeries = db.Head().NumSeries()
+	status.MaxTime = db.Head().MaxTime()
+	status.MinTime = db.Head().MaxTime()
+
 	h.executeTemplate(w, "status.html", status)
 }