fix(kubeClientSandbox): do not wait for pods in the fake indexers if they are already deleted

pkg/descheduler/kubeclientsandbox.go

@@ -215,19 +215,27 @@ func (sandbox *kubeClientSandbox) reset() {
 }
 
 // hasObjectInIndexer checks if an object exists in the fake indexer for the specified resource
-func (sandbox *kubeClientSandbox) hasObjectInIndexer(resource schema.GroupVersionResource, namespace, name string) (bool, error) {
+func (sandbox *kubeClientSandbox) hasObjectInIndexer(resource schema.GroupVersionResource, namespace, name, uid string) (bool, error) {
 	informer, err := sandbox.fakeFactory.ForResource(resource)
 	if err != nil {
 		return false, fmt.Errorf("error getting informer for resource %s: %w", resource, err)
 	}
 
 	key := cache.MetaObjectToName(&metav1.ObjectMeta{Namespace: namespace, Name: name}).String()
-	_, exists, err := informer.Informer().GetIndexer().GetByKey(key)
+	obj, exists, err := informer.Informer().GetIndexer().GetByKey(key)
 	if err != nil {
 		return false, err
 	}
 
-	return exists, nil
+	if !exists {
+		return false, nil
+	}
+
+	metaObj, err := meta.Accessor(obj)
+	if err != nil {
+		return false, fmt.Errorf("failed to get object metadata: %w", err)
+	}
+	return string(metaObj.GetUID()) == uid, nil
 }
 
 // hasRuntimeObjectInIndexer checks if a runtime.Object exists in the fake indexer by detecting its resource type
@@ -252,7 +260,28 @@ func (sandbox *kubeClientSandbox) hasRuntimeObjectInIndexer(obj runtime.Object)
 		Resource: plural.Resource,
 	}
 
-	return sandbox.hasObjectInIndexer(gvr, metaObj.GetNamespace(), metaObj.GetName())
+	return sandbox.hasObjectInIndexer(gvr, metaObj.GetNamespace(), metaObj.GetName(), string(metaObj.GetUID()))
+}
+
+// shouldSkipPodWait checks if a pod still exists in the fake client with the expected UID.
+// Returns (shouldSkip, error). shouldSkip is true if we should skip waiting for this pod.
+// Returns an error for unexpected failures (non-NotFound errors).
+func (sandbox *kubeClientSandbox) shouldSkipPodWait(ctx context.Context, pod *evictedPodInfo) (bool, error) {
+	// Check if the pod still exists in the fake client (it could have been deleted from the real client
+	// and the deletion propagated via event handlers in the meantime)
+	fakePod, err := sandbox.fakeClient().CoreV1().Pods(pod.Namespace).Get(ctx, pod.Name, metav1.GetOptions{})
+	if err != nil {
+		if apierrors.IsNotFound(err) {
+			klog.V(3).InfoS("Pod no longer exists in fake client, skipping wait", "namespace", pod.Namespace, "name", pod.Name)
+			return true, nil
+		}
+		return false, fmt.Errorf("error getting pod %s/%s from fake client: %w", pod.Namespace, pod.Name, err)
+	}
+	if string(fakePod.UID) != pod.UID {
+		klog.V(3).InfoS("Pod UID mismatch in fake client, skipping wait", "namespace", pod.Namespace, "name", pod.Name, "expectedUID", pod.UID, "actualUID", string(fakePod.UID))
+		return true, nil
+	}
+	return false, nil
 }
 
 func waitForPodsCondition(ctx context.Context, pods []*evictedPodInfo, checkFn func(*evictedPodInfo) (bool, error), successMsg string) error {
@@ -291,46 +320,48 @@ func (sandbox *kubeClientSandbox) restoreEvictedPods(ctx context.Context) error
 
 	// First wait loop: Check that all evicted pods are cleared from the indexers.
 	// This ensures the eviction has fully propagated through the fake informer's indexer.
+	// We check both existence and UID match to handle cases where a pod was deleted and
+	// recreated with the same name but different UID.
 	if err := waitForPodsCondition(ctx, evictedPods, func(pod *evictedPodInfo) (bool, error) {
-		exists, err := sandbox.hasObjectInIndexer(v1.SchemeGroupVersion.WithResource("pods"), pod.Namespace, pod.Name)
+		exists, err := sandbox.hasObjectInIndexer(v1.SchemeGroupVersion.WithResource("pods"), pod.Namespace, pod.Name, pod.UID)
 		if err != nil {
 			klog.V(4).InfoS("Error checking indexer for pod", "namespace", pod.Namespace, "name", pod.Name, "error", err)
 			return false, nil
 		}
 		if exists {
-			klog.V(4).InfoS("Pod still exists in fake indexer, waiting", "namespace", pod.Namespace, "name", pod.Name)
+			klog.V(4).InfoS("Pod with matching UID still exists in fake indexer, waiting", "namespace", pod.Namespace, "name", pod.Name, "uid", pod.UID)
 			return false, nil
 		}
-		klog.V(4).InfoS("Pod no longer in fake indexer", "namespace", pod.Namespace, "name", pod.Name)
+		klog.V(4).InfoS("Pod with matching UID no longer in fake indexer", "namespace", pod.Namespace, "name", pod.Name, "uid", pod.UID)
 		return true, nil
 	}, "All evicted pods removed from fake indexer"); err != nil {
 		return fmt.Errorf("timeout waiting for evicted pods to be removed from fake indexer: %w", err)
 	}
 
 	var restoredPods []*evictedPodInfo
-	for _, evictedPodInfo := range sandbox.evictedPodsCache.list() {
+	for _, podInfo := range sandbox.evictedPodsCache.list() {
-		obj, err := podInformer.Lister().ByNamespace(evictedPodInfo.Namespace).Get(evictedPodInfo.Name)
+		obj, err := podInformer.Lister().ByNamespace(podInfo.Namespace).Get(podInfo.Name)
 		if err != nil {
-			klog.V(3).InfoS("Pod not found in real client, skipping restoration", "namespace", evictedPodInfo.Namespace, "name", evictedPodInfo.Name, "error", err)
+			klog.V(3).InfoS("Pod not found in real client, skipping restoration", "namespace", podInfo.Namespace, "name", podInfo.Name, "error", err)
 			continue
 		}
 
 		pod, ok := obj.(*v1.Pod)
 		if !ok {
-			klog.ErrorS(nil, "Object is not a pod", "namespace", evictedPodInfo.Namespace, "name", evictedPodInfo.Name)
+			klog.ErrorS(nil, "Object is not a pod", "namespace", podInfo.Namespace, "name", podInfo.Name)
 			continue
 		}
 
-		if string(pod.UID) != evictedPodInfo.UID {
+		if string(pod.UID) != podInfo.UID {
-			klog.V(3).InfoS("Pod UID mismatch, skipping restoration", "namespace", evictedPodInfo.Namespace, "name", evictedPodInfo.Name, "expectedUID", evictedPodInfo.UID, "actualUID", string(pod.UID))
+			klog.V(3).InfoS("Pod UID mismatch, skipping restoration", "namespace", podInfo.Namespace, "name", podInfo.Name, "expectedUID", podInfo.UID, "actualUID", string(pod.UID))
 			continue
 		}
 
-		if err := sandbox.fakeKubeClient.Tracker().Add(pod); err != nil && !apierrors.IsAlreadyExists(err) {
+		if err = sandbox.fakeKubeClient.Tracker().Add(pod); err != nil && !apierrors.IsAlreadyExists(err) {
-			return fmt.Errorf("failed to restore pod %s/%s to fake client: %w", evictedPodInfo.Namespace, evictedPodInfo.Name, err)
+			return fmt.Errorf("failed to restore pod %s/%s to fake client: %w", podInfo.Namespace, podInfo.Name, err)
 		}
-		klog.V(4).InfoS("Successfully restored pod to fake client", "namespace", evictedPodInfo.Namespace, "name", evictedPodInfo.Name, "uid", evictedPodInfo.UID)
+		klog.V(4).InfoS("Successfully restored pod to fake client", "namespace", podInfo.Namespace, "name", podInfo.Name, "uid", podInfo.UID)
-		restoredPods = append(restoredPods, evictedPodInfo)
+		restoredPods = append(restoredPods, podInfo)
 	}
 
 	// Second wait loop: Make sure the evicted pods are added back to the fake client.
@@ -339,6 +370,13 @@ func (sandbox *kubeClientSandbox) restoreEvictedPods(ctx context.Context) error
 		podObj, err := sandbox.fakeFactory.Core().V1().Pods().Lister().Pods(pod.Namespace).Get(pod.Name)
 		if err != nil {
 			klog.V(4).InfoS("Pod not yet accessible in fake informer, waiting", "namespace", pod.Namespace, "name", pod.Name)
+			shouldSkip, checkErr := sandbox.shouldSkipPodWait(ctx, pod)
+			if checkErr != nil {
+				return false, checkErr
+			}
+			if shouldSkip {
+				return true, nil
+			}
 			return false, nil
 		}
 		klog.V(4).InfoS("Pod accessible in fake informer", "namespace", pod.Namespace, "name", pod.Name, "node", podObj.Spec.NodeName)
@@ -351,13 +389,20 @@ func (sandbox *kubeClientSandbox) restoreEvictedPods(ctx context.Context) error
 	// This is important to ensure each descheduling cycle can see all the restored pods.
 	// Without this wait, the next cycle might not see the restored pods in the indexer yet.
 	if err := waitForPodsCondition(ctx, restoredPods, func(pod *evictedPodInfo) (bool, error) {
-		exists, err := sandbox.hasObjectInIndexer(v1.SchemeGroupVersion.WithResource("pods"), pod.Namespace, pod.Name)
+		exists, err := sandbox.hasObjectInIndexer(v1.SchemeGroupVersion.WithResource("pods"), pod.Namespace, pod.Name, pod.UID)
 		if err != nil {
 			klog.V(4).InfoS("Error checking indexer for restored pod", "namespace", pod.Namespace, "name", pod.Name, "error", err)
 			return false, nil
 		}
 		if !exists {
 			klog.V(4).InfoS("Restored pod not yet in fake indexer, waiting", "namespace", pod.Namespace, "name", pod.Name)
+			shouldSkip, checkErr := sandbox.shouldSkipPodWait(ctx, pod)
+			if checkErr != nil {
+				return false, checkErr
+			}
+			if shouldSkip {
+				return true, nil
+			}
 			return false, nil
 		}
 		klog.V(4).InfoS("Restored pod now in fake indexer", "namespace", pod.Namespace, "name", pod.Name)

pkg/descheduler/kubeclientsandbox_test.go

@@ -125,13 +125,14 @@ func TestKubeClientSandboxEventHandlers(t *testing.T) {
 	}
 
 	// Helper function to wait for a resource to appear in the sandbox's fake client indexer
-	waitForResourceInIndexer := func(resourceType, namespace, name, description string) error {
+	waitForResourceInIndexer := func(resourceType, namespace, name, uid, description string) error {
 		t.Logf("Waiting for %s to appear in fake client indexer...", description)
 		return wait.PollUntilContextTimeout(ctx, 100*time.Millisecond, 5*time.Second, true, func(ctx context.Context) (bool, error) {
 			exists, err := sandbox.hasObjectInIndexer(
 				v1.SchemeGroupVersion.WithResource(resourceType),
 				namespace,
 				name,
+				uid,
 			)
 			if err != nil {
 				t.Logf("Error checking %s in indexer: %v", description, err)
@@ -146,12 +147,12 @@ func TestKubeClientSandboxEventHandlers(t *testing.T) {
 	}
 
 	// Wait for the pod to appear in the sandbox's fake client indexer
-	if err := waitForResourceInIndexer("pods", testPod.Namespace, testPod.Name, "pod"); err != nil {
+	if err := waitForResourceInIndexer("pods", testPod.Namespace, testPod.Name, string(testPod.UID), "pod"); err != nil {
 		t.Fatalf("Pod did not appear in fake client indexer within timeout: %v", err)
 	}
 
 	// Wait for the node to appear in the sandbox's fake client indexer
-	if err := waitForResourceInIndexer("nodes", "", testNode.Name, "node"); err != nil {
+	if err := waitForResourceInIndexer("nodes", "", testNode.Name, string(testNode.UID), "node"); err != nil {
 		t.Fatalf("Node did not appear in fake client indexer within timeout: %v", err)
 	}
 
@@ -269,6 +270,137 @@ func TestKubeClientSandboxReset(t *testing.T) {
 	t.Logf("Successfully verified cache is empty after reset")
 }
 
+func TestKubeClientSandboxRestoreEvictedPods(t *testing.T) {
+	ctx := context.Background()
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	node1 := test.BuildTestNode("n1", 2000, 3000, 10, nil)
+
+	// Create test pods
+	pod1 := test.BuildTestPod("pod1", 100, 0, node1.Name, test.SetRSOwnerRef)
+	pod2 := test.BuildTestPod("pod2", 100, 0, node1.Name, test.SetRSOwnerRef)
+	pod3 := test.BuildTestPod("pod3", 100, 0, node1.Name, test.SetRSOwnerRef)
+	pod4 := test.BuildTestPod("pod4", 100, 0, node1.Name, test.SetRSOwnerRef)
+
+	sandbox, _, realClient := setupTestSandbox(ctx, t, node1, pod1, pod2, pod3, pod4)
+
+	// Evict all pods
+	for _, pod := range []*v1.Pod{pod1, pod2, pod3, pod4} {
+		eviction := &policy.Eviction{
+			ObjectMeta: metav1.ObjectMeta{
+				Name:      pod.Name,
+				Namespace: pod.Namespace,
+			},
+		}
+		if err := sandbox.fakeClient().CoreV1().Pods(pod.Namespace).EvictV1(ctx, eviction); err != nil {
+			t.Fatalf("Error evicting %s: %v", pod.Name, err)
+		}
+	}
+
+	// Delete pod2 from real client to simulate it being deleted (should skip restoration)
+	if err := realClient.CoreV1().Pods(pod2.Namespace).Delete(ctx, pod2.Name, metav1.DeleteOptions{}); err != nil {
+		t.Fatalf("Error deleting pod2 from real client: %v", err)
+	}
+
+	// Delete and recreate pod3 with different UID in real client (should skip restoration)
+	if err := realClient.CoreV1().Pods(pod3.Namespace).Delete(ctx, pod3.Name, metav1.DeleteOptions{}); err != nil {
+		t.Fatalf("Error deleting pod3 from real client: %v", err)
+	}
+	pod3New := test.BuildTestPod("pod3", 100, 0, node1.Name, test.SetRSOwnerRef)
+	// Ensure pod3New has a different UID from pod3
+	if pod3New.UID == pod3.UID {
+		pod3New.UID = "new-uid-for-pod3"
+	}
+	if _, err := realClient.CoreV1().Pods(pod3New.Namespace).Create(ctx, pod3New, metav1.CreateOptions{}); err != nil {
+		t.Fatalf("Error recreating pod3 in real client: %v", err)
+	}
+
+	// Verify evicted pods are in cache
+	evictedPods := sandbox.evictedPodsCache.list()
+	if len(evictedPods) != 4 {
+		t.Fatalf("Expected 4 evicted pods in cache, got %d", len(evictedPods))
+	}
+	t.Logf("Evicted pods in cache: %d", len(evictedPods))
+
+	// Call restoreEvictedPods
+	t.Log("Calling restoreEvictedPods...")
+	if err := sandbox.restoreEvictedPods(ctx); err != nil {
+		t.Fatalf("restoreEvictedPods failed: %v", err)
+	}
+
+	// Verify pod1 and pod4 were restored (exists in fake client with matching UID and accessible via indexer)
+	for _, pod := range []*v1.Pod{pod1, pod4} {
+		// Check restoration via fake client
+		restoredPod, err := sandbox.fakeClient().CoreV1().Pods(pod.Namespace).Get(ctx, pod.Name, metav1.GetOptions{})
+		if err != nil {
+			t.Errorf("%s should have been restored to fake client: %v", pod.Name, err)
+		} else {
+			if restoredPod.UID != pod.UID {
+				t.Errorf("Restored %s UID mismatch: got %s, want %s", pod.Name, restoredPod.UID, pod.UID)
+			}
+			t.Logf("Successfully verified %s restoration: %s/%s (UID: %s)", pod.Name, restoredPod.Namespace, restoredPod.Name, restoredPod.UID)
+		}
+
+		// Check accessibility via indexer
+		exists, err := sandbox.hasObjectInIndexer(v1.SchemeGroupVersion.WithResource("pods"), pod.Namespace, pod.Name, string(pod.UID))
+		if err != nil {
+			t.Errorf("Error checking %s in indexer: %v", pod.Name, err)
+		}
+		if !exists {
+			t.Errorf("%s should exist in fake indexer after restoration", pod.Name)
+		} else {
+			t.Logf("Successfully verified %s exists in fake indexer", pod.Name)
+		}
+	}
+
+	// Verify pod2 was NOT restored (deleted from real client)
+	_, err := sandbox.fakeClient().CoreV1().Pods(pod2.Namespace).Get(ctx, pod2.Name, metav1.GetOptions{})
+	if err == nil {
+		t.Error("pod2 should NOT have been restored (was deleted from real client)")
+	} else {
+		t.Logf("Correctly verified pod2 was not restored: %v", err)
+	}
+
+	// Verify pod3 was NOT restored with old UID (UID mismatch case)
+	// Note: pod3 may exist in fake client with NEW UID due to event handler syncing,
+	// but it should NOT have been restored with the OLD UID from evicted cache
+	pod3InFake, err := sandbox.fakeClient().CoreV1().Pods(pod3.Namespace).Get(ctx, pod3.Name, metav1.GetOptions{})
+	if err == nil {
+		// Pod3 exists, but it should have the NEW UID, not the old one
+		if pod3InFake.UID == pod3.UID {
+			t.Error("pod3 should NOT have been restored with old UID (UID mismatch should prevent restoration)")
+		} else {
+			t.Logf("Correctly verified pod3 has new UID (%s), not old UID (%s) - restoration was skipped", pod3InFake.UID, pod3.UID)
+		}
+	} else {
+		// Pod3 doesn't exist - this is also acceptable (event handlers haven't synced it yet)
+		t.Logf("pod3 not found in fake client: %v", err)
+	}
+
+	// Verify evicted pods cache is still intact (restoreEvictedPods doesn't clear it)
+	evictedPodsAfter := sandbox.evictedPodsCache.list()
+	if len(evictedPodsAfter) != 4 {
+		t.Errorf("Expected evicted pods cache to still have 4 entries, got %d", len(evictedPodsAfter))
+	}
+}
+
+func TestKubeClientSandboxRestoreEvictedPodsEmptyCache(t *testing.T) {
+	ctx := context.Background()
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	node1 := test.BuildTestNode("n1", 2000, 3000, 10, nil)
+	sandbox, _, _ := setupTestSandbox(ctx, t, node1)
+
+	// Call restoreEvictedPods with empty cache - should be a no-op
+	t.Log("Calling restoreEvictedPods with empty cache...")
+	if err := sandbox.restoreEvictedPods(ctx); err != nil {
+		t.Fatalf("restoreEvictedPods should succeed with empty cache: %v", err)
+	}
+	t.Log("Successfully verified restoreEvictedPods handles empty cache")
+}
+
 func TestEvictedPodsCache(t *testing.T) {
 	t.Run("add single pod", func(t *testing.T) {
 		const (