Ensure that pods obey backoff timers.

pkg/scheduler/internal/queue/scheduling_queue.go

@@ -383,7 +383,8 @@ func (p *PriorityQueue) clearPodBackoff(pod *v1.Pod) {
 	p.podBackoff.ClearPodBackoff(nsNameForPod(pod))
 }
 
-// isPodBackingOff returns whether a pod is currently undergoing backoff in the podBackoff structure
+// isPodBackingOff returns true if a pod is still waiting for its backoff timer.
+// If this returns true, the pod should not be re-tried.
 func (p *PriorityQueue) isPodBackingOff(pod *v1.Pod) bool {
 	boTime, exists := p.podBackoff.GetBackoffTime(nsNameForPod(pod))
 	if !exists {
@@ -411,11 +412,10 @@ func (p *PriorityQueue) SchedulingCycle() int64 {
 	return p.schedulingCycle
 }
 
-// AddUnschedulableIfNotPresent does nothing if the pod is present in any
-// queue. If pod is unschedulable, it adds pod to unschedulable queue if
-// p.moveRequestCycle > podSchedulingCycle or to backoff queue if p.moveRequestCycle
-// <= podSchedulingCycle but pod is subject to backoff. In other cases, it adds pod to
-// active queue.
+// AddUnschedulableIfNotPresent inserts a pod that cannot be scheduled into
+// the queue, unless it is already in the queue. Normally, PriorityQueue puts
+// unschedulable pods in `unschedulableQ`. But if there has been a recent move
+// request, then the pod is put in `podBackoffQ`.
 func (p *PriorityQueue) AddUnschedulableIfNotPresent(pod *v1.Pod, podSchedulingCycle int64) error {
 	p.lock.Lock()
 	defer p.lock.Unlock()
@@ -430,30 +430,26 @@ func (p *PriorityQueue) AddUnschedulableIfNotPresent(pod *v1.Pod, podSchedulingC
 	if _, exists, _ := p.podBackoffQ.Get(pInfo); exists {
 		return fmt.Errorf("pod is already present in the backoffQ")
 	}
-	if podSchedulingCycle > p.moveRequestCycle && isPodUnschedulable(pod) {
-		p.backoffPod(pod)
-		p.unschedulableQ.addOrUpdate(pInfo)
-		p.nominatedPods.add(pod, "")
-		return nil
-	}
 
-	// If a move request has been received and the pod is subject to backoff, move it to the BackoffQ.
-	if p.isPodBackingOff(pod) && isPodUnschedulable(pod) {
-		err := p.podBackoffQ.Add(pInfo)
-		if err != nil {
-			klog.Errorf("Error adding pod %v to the backoff queue: %v", pod.Name, err)
-		} else {
-			p.nominatedPods.add(pod, "")
+	// Every unschedulable pod is subject to backoff timers.
+	p.backoffPod(pod)
+
+	// If a move request has been received, move it to the BackoffQ, otherwise move
+	// it to unschedulableQ.
+	if p.moveRequestCycle >= podSchedulingCycle {
+		if err := p.podBackoffQ.Add(pInfo); err != nil {
+			// TODO: Delete this klog call and log returned errors at the call site.
+			err = fmt.Errorf("error adding pod %v to the backoff queue: %v", pod.Name, err)
+			klog.Error(err)
+			return err
 		}
-		return err
+	} else {
+		p.unschedulableQ.addOrUpdate(pInfo)
 	}
 
-	err := p.activeQ.Add(pInfo)
-	if err == nil {
-		p.nominatedPods.add(pod, "")
-		p.cond.Broadcast()
-	}
-	return err
+	p.nominatedPods.add(pod, "")
+	return nil
+
 }
 
 // flushBackoffQCompleted Moves all pods from backoffQ which have completed backoff in to activeQ

pkg/scheduler/internal/queue/scheduling_queue_test.go

@@ -184,16 +184,14 @@ func TestPriorityQueue_AddUnschedulableIfNotPresent(t *testing.T) {
 	q := NewPriorityQueue(nil)
 	q.Add(&highPriNominatedPod)
 	q.AddUnschedulableIfNotPresent(&highPriNominatedPod, q.SchedulingCycle()) // Must not add anything.
-	q.AddUnschedulableIfNotPresent(&medPriorityPod, q.SchedulingCycle())      // This should go to activeQ.
 	q.AddUnschedulableIfNotPresent(&unschedulablePod, q.SchedulingCycle())
 	expectedNominatedPods := &nominatedPodMap{
 		nominatedPodToNode: map[types.UID]string{
-			medPriorityPod.UID:      "node1",
 			unschedulablePod.UID:    "node1",
 			highPriNominatedPod.UID: "node1",
 		},
 		nominatedPods: map[string][]*v1.Pod{
-			"node1": {&highPriNominatedPod, &medPriorityPod, &unschedulablePod},
+			"node1": {&highPriNominatedPod, &unschedulablePod},
 		},
 	}
 	if !reflect.DeepEqual(q.nominatedPods, expectedNominatedPods) {
@@ -202,9 +200,6 @@ func TestPriorityQueue_AddUnschedulableIfNotPresent(t *testing.T) {
 	if p, err := q.Pop(); err != nil || p != &highPriNominatedPod {
 		t.Errorf("Expected: %v after Pop, but got: %v", highPriNominatedPod.Name, p.Name)
 	}
-	if p, err := q.Pop(); err != nil || p != &medPriorityPod {
-		t.Errorf("Expected: %v after Pop, but got: %v", medPriorityPod.Name, p.Name)
-	}
 	if len(q.nominatedPods.nominatedPods) != 1 {
 		t.Errorf("Expected nomindatePods to have one element: %v", q.nominatedPods)
 	}
@@ -213,11 +208,11 @@ func TestPriorityQueue_AddUnschedulableIfNotPresent(t *testing.T) {
 	}
 }
 
-// TestPriorityQueue_AddUnschedulableIfNotPresent_Async tests scenario when
+// TestPriorityQueue_AddUnschedulableIfNotPresent_Backoff tests scenario when
 // AddUnschedulableIfNotPresent is called asynchronously pods in and before
 // current scheduling cycle will be put back to activeQueue if we were trying
 // to schedule them when we received move request.
-func TestPriorityQueue_AddUnschedulableIfNotPresent_Async(t *testing.T) {
+func TestPriorityQueue_AddUnschedulableIfNotPresent_Backoff(t *testing.T) {
 	q := NewPriorityQueue(nil)
 	totalNum := 10
 	expectedPods := make([]v1.Pod, 0, totalNum)
@@ -248,10 +243,14 @@ func TestPriorityQueue_AddUnschedulableIfNotPresent_Async(t *testing.T) {
 
 	// move all pods to active queue when we were trying to schedule them
 	q.MoveAllToActiveQueue()
-	moveReqChan := make(chan struct{})
-	var wg sync.WaitGroup
-	wg.Add(totalNum - 1)
-	// mark pods[1] ~ pods[totalNum-1] as unschedulable, fire goroutines to add them back later
+	oldCycle := q.SchedulingCycle()
+
+	firstPod, _ := q.Pop()
+	if !reflect.DeepEqual(&expectedPods[0], firstPod) {
+		t.Errorf("Unexpected pod. Expected: %v, got: %v", &expectedPods[0], firstPod)
+	}
+
+	// mark pods[1] ~ pods[totalNum-1] as unschedulable and add them back
 	for i := 1; i < totalNum; i++ {
 		unschedulablePod := expectedPods[i].DeepCopy()
 		unschedulablePod.Status = v1.PodStatus{
@@ -263,24 +262,15 @@ func TestPriorityQueue_AddUnschedulableIfNotPresent_Async(t *testing.T) {
 				},
 			},
 		}
-		cycle := q.SchedulingCycle()
-		go func() {
-			<-moveReqChan
-			q.AddUnschedulableIfNotPresent(unschedulablePod, cycle)
-			wg.Done()
-		}()
-	}
-	firstPod, _ := q.Pop()
-	if !reflect.DeepEqual(&expectedPods[0], firstPod) {
-		t.Errorf("Unexpected pod. Expected: %v, got: %v", &expectedPods[0], firstPod)
+
+		q.AddUnschedulableIfNotPresent(unschedulablePod, oldCycle)
 	}
-	// close moveReqChan here to make sure q.AddUnschedulableIfNotPresent is called after another pod is popped
-	close(moveReqChan)
-	wg.Wait()
-	// all other pods should be in active queue again
+
+	// Since there was a move request at the same cycle as "oldCycle", these pods
+	// should be in the backoff queue.
 	for i := 1; i < totalNum; i++ {
-		if _, exists, _ := q.activeQ.Get(newPodInfoNoTimestamp(&expectedPods[i])); !exists {
-			t.Errorf("Expected %v to be added to activeQ.", expectedPods[i].Name)
+		if _, exists, _ := q.podBackoffQ.Get(newPodInfoNoTimestamp(&expectedPods[i])); !exists {
+			t.Errorf("Expected %v to be added to podBackoffQ.", expectedPods[i].Name)
 		}
 	}
 }