[release-1.9] Scheduler doesn't reschedule vpods that are scheduled on unscehdulable pods

pkg/scheduler/state/state.go

@@ -135,6 +135,15 @@ func (s *State) GetPodInfo(podName string) (zoneName string, nodeName string, er
 	return zoneName, nodeName, nil
 }
 
+func (s *State) IsSchedulablePod(ordinal int32) bool {
+	for _, x := range s.SchedulablePods {
+		if x == ordinal {
+			return true
+		}
+	}
+	return false
+}
+
 // stateBuilder reconstruct the state from scratch, by listing vpods
 type stateBuilder struct {
 	ctx               context.Context

pkg/scheduler/statefulset/scheduler.go

@@ -177,10 +177,20 @@ func (s *StatefulSetScheduler) scheduleVPod(vpod scheduler.VPod) ([]duckv1alpha1
 		return nil, err
 	}
 
-	placements := vpod.GetPlacements()
-	existingPlacements := placements
+	existingPlacements := vpod.GetPlacements()
 	var left int32
 
+	// Remove unschedulable pods from placements
+	var placements []duckv1alpha1.Placement
+	if len(existingPlacements) > 0 {
+		placements = make([]duckv1alpha1.Placement, 0, len(existingPlacements))
+		for _, p := range existingPlacements {
+			if state.IsSchedulablePod(st.OrdinalFromPodName(p.PodName)) {
+				placements = append(placements, *p.DeepCopy())
+			}
+		}
+	}
+
 	// The scheduler when policy type is
 	// Policy: MAXFILLUP (SchedulerPolicyType == MAXFILLUP)
 	// - allocates as many vreplicas as possible to the same pod(s)

pkg/scheduler/statefulset/scheduler_test.go

@@ -87,6 +87,32 @@ func TestStatefulsetScheduler(t *testing.T) {
 			expected:            []duckv1alpha1.Placement{{PodName: "statefulset-name-0", VReplicas: 3}},
 			schedulerPolicyType: scheduler.MAXFILLUP,
 		},
+		{
+			name:      "one replica, 8 vreplicas, already scheduled on unschedulable pod, add replicas",
+			vreplicas: 8,
+			replicas:  int32(1),
+			placements: []duckv1alpha1.Placement{
+				{PodName: "statefulset-name-0", VReplicas: 3},
+				{PodName: "statefulset-name-2", VReplicas: 5},
+			},
+			expected: []duckv1alpha1.Placement{
+				{PodName: "statefulset-name-0", VReplicas: 8},
+			},
+			schedulerPolicyType: scheduler.MAXFILLUP,
+		},
+		{
+			name:      "one replica, 1 vreplicas, already scheduled on unschedulable pod, remove replicas",
+			vreplicas: 1,
+			replicas:  int32(1),
+			placements: []duckv1alpha1.Placement{
+				{PodName: "statefulset-name-0", VReplicas: 3},
+				{PodName: "statefulset-name-2", VReplicas: 5},
+			},
+			expected: []duckv1alpha1.Placement{
+				{PodName: "statefulset-name-0", VReplicas: 1},
+			},
+			schedulerPolicyType: scheduler.MAXFILLUP,
+		},
 		{
 			name:                "one replica, 15 vreplicas, unschedulable",
 			vreplicas:           15,