add metrics to record number of pending pods in different queues

Author: Huang-Wei

pkg/scheduler/internal/queue/scheduling_queue.go

@@ -42,6 +42,7 @@ import (
 	podutil "k8s.io/kubernetes/pkg/api/v1/pod"
 	"k8s.io/kubernetes/pkg/scheduler/algorithm/predicates"
 	priorityutil "k8s.io/kubernetes/pkg/scheduler/algorithm/priorities/util"
+	"k8s.io/kubernetes/pkg/scheduler/metrics"
 	"k8s.io/kubernetes/pkg/scheduler/util"
 )
 
@@ -283,13 +284,13 @@ func NewPriorityQueueWithClock(stop <-chan struct{}, clock util.Clock) *Priority
 		clock:            clock,
 		stop:             stop,
 		podBackoff:       NewPodBackoffMap(1*time.Second, 10*time.Second),
-		activeQ:          util.NewHeap(podInfoKeyFunc, activeQComp),
-		unschedulableQ:   newUnschedulablePodsMap(),
+		activeQ:          util.NewHeapWithRecorder(podInfoKeyFunc, activeQComp, metrics.NewActivePodsRecorder()),
+		unschedulableQ:   newUnschedulablePodsMap(metrics.NewUnschedulablePodsRecorder()),
 		nominatedPods:    newNominatedPodMap(),
 		moveRequestCycle: -1,
 	}
 	pq.cond.L = &pq.lock
-	pq.podBackoffQ = util.NewHeap(podInfoKeyFunc, pq.podsCompareBackoffCompleted)
+	pq.podBackoffQ = util.NewHeapWithRecorder(podInfoKeyFunc, pq.podsCompareBackoffCompleted, metrics.NewBackoffPodsRecorder())
 
 	pq.run()
 
@@ -777,16 +778,27 @@ type UnschedulablePodsMap struct {
 	// podInfoMap is a map key by a pod's full-name and the value is a pointer to the podInfo.
 	podInfoMap map[string]*podInfo
 	keyFunc    func(*v1.Pod) string
+	// metricRecorder updates the counter when elements of an unschedulablePodsMap
+	// get added or removed, and it does nothing if it's nil
+	metricRecorder metrics.MetricRecorder
 }
 
 // Add adds a pod to the unschedulable podInfoMap.
 func (u *UnschedulablePodsMap) addOrUpdate(pInfo *podInfo) {
-	u.podInfoMap[u.keyFunc(pInfo.pod)] = pInfo
+	podID := u.keyFunc(pInfo.pod)
+	if _, exists := u.podInfoMap[podID]; !exists && u.metricRecorder != nil {
+		u.metricRecorder.Inc()
+	}
+	u.podInfoMap[podID] = pInfo
 }
 
 // Delete deletes a pod from the unschedulable podInfoMap.
 func (u *UnschedulablePodsMap) delete(pod *v1.Pod) {
-	delete(u.podInfoMap, u.keyFunc(pod))
+	podID := u.keyFunc(pod)
+	if _, exists := u.podInfoMap[podID]; exists && u.metricRecorder != nil {
+		u.metricRecorder.Dec()
+	}
+	delete(u.podInfoMap, podID)
 }
 
 // Get returns the podInfo if a pod with the same key as the key of the given "pod"
@@ -802,13 +814,17 @@ func (u *UnschedulablePodsMap) get(pod *v1.Pod) *podInfo {
 // Clear removes all the entries from the unschedulable podInfoMap.
 func (u *UnschedulablePodsMap) clear() {
 	u.podInfoMap = make(map[string]*podInfo)
+	if u.metricRecorder != nil {
+		u.metricRecorder.Clear()
+	}
 }
 
 // newUnschedulablePodsMap initializes a new object of UnschedulablePodsMap.
-func newUnschedulablePodsMap() *UnschedulablePodsMap {
+func newUnschedulablePodsMap(metricRecorder metrics.MetricRecorder) *UnschedulablePodsMap {
 	return &UnschedulablePodsMap{
-		podInfoMap: make(map[string]*podInfo),
-		keyFunc:    util.GetPodFullName,
+		podInfoMap:     make(map[string]*podInfo),
+		keyFunc:        util.GetPodFullName,
+		metricRecorder: metricRecorder,
 	}
 }
 

pkg/scheduler/internal/queue/scheduling_queue_test.go

@@ -647,7 +647,7 @@ func TestUnschedulablePodsMap(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			upm := newUnschedulablePodsMap()
+			upm := newUnschedulablePodsMap(nil)
 			for _, p := range test.podsToAdd {
 				upm.addOrUpdate(newPodInfoNoTimestamp(p))
 			}

pkg/scheduler/metrics/metric_recorder.go

@@ -0,0 +1,72 @@
+/*
+Copyright 2019 The Kubernetes 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 metrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// MetricRecorder represents a metric recorder which takes action when the
+// metric Inc(), Dec() and Clear()
+type MetricRecorder interface {
+	Inc()
+	Dec()
+	Clear()
+}
+
+var _ MetricRecorder = &PendingPodsRecorder{}
+
+// PendingPodsRecorder is an implementation of MetricRecorder
+type PendingPodsRecorder struct {
+	recorder prometheus.Gauge
+}
+
+// NewActivePodsRecorder returns ActivePods in a Prometheus metric fashion
+func NewActivePodsRecorder() *PendingPodsRecorder {
+	return &PendingPodsRecorder{
+		recorder: ActivePods,
+	}
+}
+
+// NewUnschedulablePodsRecorder returns UnschedulablePods in a Prometheus metric fashion
+func NewUnschedulablePodsRecorder() *PendingPodsRecorder {
+	return &PendingPodsRecorder{
+		recorder: UnschedulablePods,
+	}
+}
+
+// NewBackoffPodsRecorder returns BackoffPods in a Prometheus metric fashion
+func NewBackoffPodsRecorder() *PendingPodsRecorder {
+	return &PendingPodsRecorder{
+		recorder: BackoffPods,
+	}
+}
+
+// Inc increases a metric counter by 1, in an atomic way
+func (r *PendingPodsRecorder) Inc() {
+	r.recorder.Inc()
+}
+
+// Dec decreases a metric counter by 1, in an atomic way
+func (r *PendingPodsRecorder) Dec() {
+	r.recorder.Dec()
+}
+
+// Clear set a metric counter to 0, in an atomic way
+func (r *PendingPodsRecorder) Clear() {
+	r.recorder.Set(float64(0))
+}

pkg/scheduler/metrics/metric_recorder_test.go

@@ -0,0 +1,103 @@
+/*
+Copyright 2019 The Kubernetes 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 metrics
+
+import (
+	"sync"
+	"sync/atomic"
+	"testing"
+)
+
+var _ MetricRecorder = &fakePodsRecorder{}
+
+type fakePodsRecorder struct {
+	counter int64
+}
+
+func (r *fakePodsRecorder) Inc() {
+	atomic.AddInt64(&r.counter, 1)
+}
+
+func (r *fakePodsRecorder) Dec() {
+	atomic.AddInt64(&r.counter, -1)
+}
+
+func (r *fakePodsRecorder) Clear() {
+	atomic.StoreInt64(&r.counter, 0)
+}
+
+func TestInc(t *testing.T) {
+	fakeRecorder := fakePodsRecorder{}
+	var wg sync.WaitGroup
+	loops := 100
+	wg.Add(loops)
+	for i := 0; i < loops; i++ {
+		go func() {
+			fakeRecorder.Inc()
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+	if fakeRecorder.counter != int64(loops) {
+		t.Errorf("Expected %v, got %v", loops, fakeRecorder.counter)
+	}
+}
+
+func TestDec(t *testing.T) {
+	fakeRecorder := fakePodsRecorder{counter: 100}
+	var wg sync.WaitGroup
+	loops := 100
+	wg.Add(loops)
+	for i := 0; i < loops; i++ {
+		go func() {
+			fakeRecorder.Dec()
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+	if fakeRecorder.counter != int64(0) {
+		t.Errorf("Expected %v, got %v", loops, fakeRecorder.counter)
+	}
+}
+
+func TestClear(t *testing.T) {
+	fakeRecorder := fakePodsRecorder{}
+	var wg sync.WaitGroup
+	incLoops, decLoops := 100, 80
+	wg.Add(incLoops + decLoops)
+	for i := 0; i < incLoops; i++ {
+		go func() {
+			fakeRecorder.Inc()
+			wg.Done()
+		}()
+	}
+	for i := 0; i < decLoops; i++ {
+		go func() {
+			fakeRecorder.Dec()
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+	if fakeRecorder.counter != int64(incLoops-decLoops) {
+		t.Errorf("Expected %v, got %v", incLoops-decLoops, fakeRecorder.counter)
+	}
+	// verify Clear() works
+	fakeRecorder.Clear()
+	if fakeRecorder.counter != int64(0) {
+		t.Errorf("Expected %v, got %v", 0, fakeRecorder.counter)
+	}
+}

pkg/scheduler/metrics/metrics.go

@@ -192,6 +192,16 @@ var (
 			Help:      "Total preemption attempts in the cluster till now",
 		})
 
+	pendingPods = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Subsystem: SchedulerSubsystem,
+			Name:      "pending_pods_total",
+			Help:      "Number of pending pods, by the queue type. 'active' means number of pods in activeQ; 'backoff' means number of pods in backoffQ; 'unschedulable' means number of pods in unschedulableQ.",
+		}, []string{"queue"})
+	ActivePods        = pendingPods.With(prometheus.Labels{"queue": "active"})
+	BackoffPods       = pendingPods.With(prometheus.Labels{"queue": "backoff"})
+	UnschedulablePods = pendingPods.With(prometheus.Labels{"queue": "unschedulable"})
+
 	metricsList = []prometheus.Collector{
 		scheduleAttempts,
 		SchedulingLatency,
@@ -210,6 +220,7 @@ var (
 		DeprecatedSchedulingAlgorithmPremptionEvaluationDuration,
 		PreemptionVictims,
 		PreemptionAttempts,
+		pendingPods,
 	}
 )
 

pkg/scheduler/util/heap.go

@@ -25,6 +25,7 @@ import (
 	"fmt"
 
 	"k8s.io/client-go/tools/cache"
+	"k8s.io/kubernetes/pkg/scheduler/metrics"
 )
 
 // KeyFunc is a function type to get the key from an object.
@@ -127,6 +128,9 @@ type Heap struct {
 	// data stores objects and has a queue that keeps their ordering according
 	// to the heap invariant.
 	data *heapData
+	// metricRecorder updates the counter when elements of a heap get added or
+	// removed, and it does nothing if it's nil
+	metricRecorder metrics.MetricRecorder
 }
 
 // Add inserts an item, and puts it in the queue. The item is updated if it
@@ -141,6 +145,9 @@ func (h *Heap) Add(obj interface{}) error {
 		heap.Fix(h.data, h.data.items[key].index)
 	} else {
 		heap.Push(h.data, &itemKeyValue{key, obj})
+		if h.metricRecorder != nil {
+			h.metricRecorder.Inc()
+		}
 	}
 	return nil
 }
@@ -154,6 +161,9 @@ func (h *Heap) AddIfNotPresent(obj interface{}) error {
 	}
 	if _, exists := h.data.items[key]; !exists {
 		heap.Push(h.data, &itemKeyValue{key, obj})
+		if h.metricRecorder != nil {
+			h.metricRecorder.Inc()
+		}
 	}
 	return nil
 }
@@ -172,6 +182,9 @@ func (h *Heap) Delete(obj interface{}) error {
 	}
 	if item, ok := h.data.items[key]; ok {
 		heap.Remove(h.data, item.index)
+		if h.metricRecorder != nil {
+			h.metricRecorder.Dec()
+		}
 		return nil
 	}
 	return fmt.Errorf("object not found")
@@ -186,6 +199,9 @@ func (h *Heap) Peek() interface{} {
 func (h *Heap) Pop() (interface{}, error) {
 	obj := heap.Pop(h.data)
 	if obj != nil {
+		if h.metricRecorder != nil {
+			h.metricRecorder.Dec()
+		}
 		return obj, nil
 	}
 	return nil, fmt.Errorf("object was removed from heap data")
@@ -225,12 +241,18 @@ func (h *Heap) Len() int {
 
 // NewHeap returns a Heap which can be used to queue up items to process.
 func NewHeap(keyFn KeyFunc, lessFn LessFunc) *Heap {
+	return NewHeapWithRecorder(keyFn, lessFn, nil)
+}
+
+// NewHeapWithRecorder wraps an optional metricRecorder to compose a Heap object.
+func NewHeapWithRecorder(keyFn KeyFunc, lessFn LessFunc, metricRecorder metrics.MetricRecorder) *Heap {
 	return &Heap{
 		data: &heapData{
 			items:    map[string]*heapItem{},
 			queue:    []string{},
 			keyFunc:  keyFn,
 			lessFunc: lessFn,
 		},
+		metricRecorder: metricRecorder,
 	}
 }