Merge pull request #124642 from wojtek-t/resilient_watchcache_initialization

Implement ResilientWatchCacheInitialization

pkg/features/kube_features.go

@@ -1236,6 +1236,8 @@ var defaultKubernetesFeatureGates = map[featuregate.Feature]featuregate.FeatureS
 
 	genericfeatures.RemainingItemCount: {Default: true, PreRelease: featuregate.GA, LockToDefault: true},
 
+	genericfeatures.ResilientWatchCacheInitialization: {Default: true, PreRelease: featuregate.Beta},
+
 	genericfeatures.SeparateCacheWatchRPC: {Default: true, PreRelease: featuregate.Beta},
 
 	genericfeatures.ServerSideApply: {Default: true, PreRelease: featuregate.GA, LockToDefault: true}, // remove in 1.29

staging/src/k8s.io/apiextensions-apiserver/test/integration/change_test.go

@@ -59,9 +59,74 @@ func TestChangeCRD(t *testing.T) {
 	ns := "default"
 	noxuNamespacedResourceClient := newNamespacedCustomResourceVersionedClient(ns, dynamicClient, noxuDefinition, "v1beta1")
 
-	stopChan := make(chan struct{})
+	updateCRD := func() {
+		noxuDefinitionToUpdate, err := apiExtensionsClient.ApiextensionsV1().CustomResourceDefinitions().Get(context.TODO(), noxuDefinition.Name, metav1.GetOptions{})
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		if len(noxuDefinitionToUpdate.Spec.Versions) == 1 {
+			v2 := noxuDefinitionToUpdate.Spec.Versions[0]
+			v2.Name = "v2"
+			v2.Served = true
+			v2.Storage = false
+			noxuDefinitionToUpdate.Spec.Versions = append(noxuDefinitionToUpdate.Spec.Versions, v2)
+		} else {
+			noxuDefinitionToUpdate.Spec.Versions = noxuDefinitionToUpdate.Spec.Versions[0:1]
+		}
+		if _, err := apiExtensionsClient.ApiextensionsV1().CustomResourceDefinitions().Update(context.TODO(), noxuDefinitionToUpdate, metav1.UpdateOptions{}); err != nil && !apierrors.IsConflict(err) {
+			t.Error(err)
+		}
+	}
 
+	// Set up 10 watchers for custom resource.
+	// We can't exercise them in a loop the same way as get requests, as watchcache
+	// can reject them with 429 and Retry-After: 1 if it is uninitialized and even
+	// though 429 is automatically retried, with frequent watchcache terminations and
+	// reinitializations they could either end-up being rejected N times and fail or
+	// or not initialize until the last watchcache reinitialization and then not be
+	// terminated. Thus we exercise their termination explicitly at the beginning.
 	wg := &sync.WaitGroup{}
+	for i := 0; i < 10; i++ {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+
+			w, err := noxuNamespacedResourceClient.Watch(context.TODO(), metav1.ListOptions{})
+			if err != nil {
+				t.Errorf("unexpected error establishing watch: %v", err)
+				return
+			}
+			for event := range w.ResultChan() {
+				switch event.Type {
+				case watch.Added, watch.Modified, watch.Deleted:
+					// all expected
+				default:
+					t.Errorf("unexpected watch event: %#v", event)
+				}
+			}
+		}(i)
+	}
+
+	// Let all the established watches soak request loops soak
+	time.Sleep(5 * time.Second)
+
+	// Update CRD and ensure that all watches are gracefully terminated.
+	updateCRD()
+
+	drained := make(chan struct{})
+	go func() {
+		defer close(drained)
+		wg.Wait()
+	}()
+
+	select {
+	case <-drained:
+	case <-time.After(wait.ForeverTestTimeout):
+		t.Fatal("timed out waiting for watchers to be terminated")
+	}
+
+	stopChan := make(chan struct{})
 
 	// Set up loop to modify CRD in the background
 	wg.Add(1)
@@ -76,28 +141,11 @@ func TestChangeCRD(t *testing.T) {
 
 			time.Sleep(10 * time.Millisecond)
 
-			noxuDefinitionToUpdate, err := apiExtensionsClient.ApiextensionsV1().CustomResourceDefinitions().Get(context.TODO(), noxuDefinition.Name, metav1.GetOptions{})
-			if err != nil {
-				t.Error(err)
-				continue
-			}
-			if len(noxuDefinitionToUpdate.Spec.Versions) == 1 {
-				v2 := noxuDefinitionToUpdate.Spec.Versions[0]
-				v2.Name = "v2"
-				v2.Served = true
-				v2.Storage = false
-				noxuDefinitionToUpdate.Spec.Versions = append(noxuDefinitionToUpdate.Spec.Versions, v2)
-			} else {
-				noxuDefinitionToUpdate.Spec.Versions = noxuDefinitionToUpdate.Spec.Versions[0:1]
-			}
-			if _, err := apiExtensionsClient.ApiextensionsV1().CustomResourceDefinitions().Update(context.TODO(), noxuDefinitionToUpdate, metav1.UpdateOptions{}); err != nil && !apierrors.IsConflict(err) {
-				t.Error(err)
-				continue
-			}
+			updateCRD()
 		}
 	}()
 
-	// Set up 10 loops creating and reading and watching custom resources
+	// Set up 10 loops creating and reading custom resources
 	for i := 0; i < 10; i++ {
 		wg.Add(1)
 		go func(i int) {
@@ -120,32 +168,6 @@ func TestChangeCRD(t *testing.T) {
 				}
 			}
 		}(i)
-
-		wg.Add(1)
-		go func(i int) {
-			defer wg.Done()
-			for {
-				time.Sleep(10 * time.Millisecond)
-				select {
-				case <-stopChan:
-					return
-				default:
-					w, err := noxuNamespacedResourceClient.Watch(context.TODO(), metav1.ListOptions{})
-					if err != nil {
-						t.Errorf("unexpected error establishing watch: %v", err)
-						continue
-					}
-					for event := range w.ResultChan() {
-						switch event.Type {
-						case watch.Added, watch.Modified, watch.Deleted:
-							// all expected
-						default:
-							t.Errorf("unexpected watch event: %#v", event)
-						}
-					}
-				}
-			}
-		}(i)
 	}
 
 	// Let all the established get request loops soak
@@ -155,7 +177,7 @@ func TestChangeCRD(t *testing.T) {
 	close(stopChan)
 
 	// Let loops drain
-	drained := make(chan struct{})
+	drained = make(chan struct{})
 	go func() {
 		defer close(drained)
 		wg.Wait()
@@ -164,6 +186,6 @@ func TestChangeCRD(t *testing.T) {
 	select {
 	case <-drained:
 	case <-time.After(wait.ForeverTestTimeout):
-		t.Error("timed out waiting for clients to complete")
+		t.Fatal("timed out waiting for clients to complete")
 	}
 }

staging/src/k8s.io/apiserver/pkg/features/kube_features.go

@@ -173,6 +173,13 @@ const (
 	// to a chunking list request.
 	RemainingItemCount featuregate.Feature = "RemainingItemCount"
 
+	// owner: @wojtek-t
+	// beta: v1.31
+	//
+	// Enables resilient watchcache initialization to avoid controlplane
+	// overload.
+	ResilientWatchCacheInitialization featuregate.Feature = "ResilientWatchCacheInitialization"
+
 	// owner: @serathius
 	// beta: v1.30
 	//
@@ -353,6 +360,8 @@ var defaultKubernetesFeatureGates = map[featuregate.Feature]featuregate.FeatureS
 
 	RemainingItemCount: {Default: true, PreRelease: featuregate.GA, LockToDefault: true}, // remove in 1.32
 
+	ResilientWatchCacheInitialization: {Default: true, PreRelease: featuregate.Beta},
+
 	RetryGenerateName: {Default: true, PreRelease: featuregate.Beta},
 
 	SeparateCacheWatchRPC: {Default: true, PreRelease: featuregate.Beta},

staging/src/k8s.io/apiserver/pkg/storage/cacher/cacher.go

@@ -532,9 +532,18 @@ func (c *Cacher) Watch(ctx context.Context, key string, opts storage.ListOptions
 		return nil, err
 	}
 
-	readyGeneration, err := c.ready.waitAndReadGeneration(ctx)
-	if err != nil {
-		return nil, errors.NewServiceUnavailable(err.Error())
+	var readyGeneration int
+	if utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		var ok bool
+		readyGeneration, ok = c.ready.checkAndReadGeneration()
+		if !ok {
+			return nil, errors.NewTooManyRequests("storage is (re)initializing", 1)
+		}
+	} else {
+		readyGeneration, err = c.ready.waitAndReadGeneration(ctx)
+		if err != nil {
+			return nil, errors.NewServiceUnavailable(err.Error())
+		}
 	}
 
 	// determine the namespace and name scope of the watch, first from the request, secondarily from the field selector
@@ -676,6 +685,14 @@ func (c *Cacher) Get(ctx context.Context, key string, opts storage.GetOptions, o
 		return c.storage.Get(ctx, key, opts, objPtr)
 	}
 
+	if utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if !c.ready.check() {
+			// If Cache is not initialized, delegate Get requests to storage
+			// as described in https://kep.k8s.io/4568
+			return c.storage.Get(ctx, key, opts, objPtr)
+		}
+	}
+
 	// If resourceVersion is specified, serve it from cache.
 	// It's guaranteed that the returned value is at least that
 	// fresh as the given resourceVersion.
@@ -684,16 +701,18 @@ func (c *Cacher) Get(ctx context.Context, key string, opts storage.GetOptions, o
 		return err
 	}
 
-	if getRV == 0 && !c.ready.check() {
-		// If Cacher is not yet initialized and we don't require any specific
-		// minimal resource version, simply forward the request to storage.
-		return c.storage.Get(ctx, key, opts, objPtr)
-	}
-
 	// Do not create a trace - it's not for free and there are tons
 	// of Get requests. We can add it if it will be really needed.
-	if err := c.ready.wait(ctx); err != nil {
-		return errors.NewServiceUnavailable(err.Error())
+
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if getRV == 0 && !c.ready.check() {
+			// If Cacher is not yet initialized and we don't require any specific
+			// minimal resource version, simply forward the request to storage.
+			return c.storage.Get(ctx, key, opts, objPtr)
+		}
+		if err := c.ready.wait(ctx); err != nil {
+			return errors.NewServiceUnavailable(err.Error())
+		}
 	}
 
 	objVal, err := conversion.EnforcePtr(objPtr)
@@ -743,6 +762,14 @@ func shouldDelegateList(opts storage.ListOptions) bool {
 	return consistentReadFromStorage || hasContinuation || hasLimit || unsupportedMatch
 }
 
+func shouldDelegateListOnNotReadyCache(opts storage.ListOptions) bool {
+	pred := opts.Predicate
+	noLabelSelector := pred.Label == nil || pred.Label.Empty()
+	noFieldSelector := pred.Field == nil || pred.Field.Empty()
+	hasLimit := pred.Limit > 0
+	return noLabelSelector && noFieldSelector && hasLimit
+}
+
 func (c *Cacher) listItems(ctx context.Context, listRV uint64, key string, pred storage.SelectionPredicate, recursive bool) ([]interface{}, uint64, string, error) {
 	if !recursive {
 		obj, exists, readResourceVersion, err := c.watchCache.WaitUntilFreshAndGet(ctx, listRV, key)
@@ -770,10 +797,19 @@ func (c *Cacher) GetList(ctx context.Context, key string, opts storage.ListOptio
 	if err != nil {
 		return err
 	}
-	if listRV == 0 && !c.ready.check() {
-		// If Cacher is not yet initialized and we don't require any specific
-		// minimal resource version, simply forward the request to storage.
-		return c.storage.GetList(ctx, key, opts, listObj)
+
+	if utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if !c.ready.check() && shouldDelegateListOnNotReadyCache(opts) {
+			// If Cacher is not initialized, delegate List requests to storage
+			// as described in https://kep.k8s.io/4568
+			return c.storage.GetList(ctx, key, opts, listObj)
+		}
+	} else {
+		if listRV == 0 && !c.ready.check() {
+			// If Cacher is not yet initialized and we don't require any specific
+			// minimal resource version, simply forward the request to storage.
+			return c.storage.GetList(ctx, key, opts, listObj)
+		}
 	}
 	requestWatchProgressSupported := etcdfeature.DefaultFeatureSupportChecker.Supports(storage.RequestWatchProgress)
 	if resourceVersion == "" && utilfeature.DefaultFeatureGate.Enabled(features.ConsistentListFromCache) && requestWatchProgressSupported {
@@ -788,8 +824,16 @@ func (c *Cacher) GetList(ctx context.Context, key string, opts storage.ListOptio
 		attribute.Stringer("type", c.groupResource))
 	defer span.End(500 * time.Millisecond)
 
-	if err := c.ready.wait(ctx); err != nil {
-		return errors.NewServiceUnavailable(err.Error())
+	if utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if !c.ready.check() {
+			// If Cacher is not initialized, reject List requests
+			// as described in https://kep.k8s.io/4568
+			return errors.NewTooManyRequests("storage is (re)initializing", 1)
+		}
+	} else {
+		if err := c.ready.wait(ctx); err != nil {
+			return errors.NewServiceUnavailable(err.Error())
+		}
 	}
 	span.AddEvent("Ready")
 

staging/src/k8s.io/apiserver/pkg/storage/cacher/cacher_test.go

@@ -464,14 +464,25 @@ func testSetupWithEtcdServer(t *testing.T, opts ...setupOption) (context.Context
 		t.Fatalf("Failed to inject list errors: %v", err)
 	}
 
+	if utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		// The tests assume that Get/GetList/Watch calls shouldn't fail.
+		// However, 429 error can now be returned if watchcache is under initialization.
+		// To avoid rewriting all tests, we wait for watcache to initialize.
+		if err := cacher.ready.wait(ctx); err != nil {
+			t.Fatal(err)
+		}
+	}
+
 	return ctx, cacher, server, terminate
 }
 
 func testSetupWithEtcdAndCreateWrapper(t *testing.T, opts ...setupOption) (storage.Interface, tearDownFunc) {
 	_, cacher, _, tearDown := testSetupWithEtcdServer(t, opts...)
 
-	if err := cacher.ready.wait(context.TODO()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.TODO()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 	return &createWrapper{Cacher: cacher}, tearDown
 }

staging/src/k8s.io/apiserver/pkg/storage/cacher/cacher_whitebox_test.go

@@ -53,7 +53,7 @@ import (
 	"k8s.io/utils/pointer"
 )
 
-func newTestCacher(s storage.Interface) (*Cacher, storage.Versioner, error) {
+func newTestCacherWithoutSyncing(s storage.Interface) (*Cacher, storage.Versioner, error) {
 	prefix := "pods"
 	config := Config{
 		Storage:        s,
@@ -79,9 +79,27 @@ func newTestCacher(s storage.Interface) (*Cacher, storage.Versioner, error) {
 		Clock:       clock.RealClock{},
 	}
 	cacher, err := NewCacherFromConfig(config)
+
 	return cacher, storage.APIObjectVersioner{}, err
 }
 
+func newTestCacher(s storage.Interface) (*Cacher, storage.Versioner, error) {
+	cacher, versioner, err := newTestCacherWithoutSyncing(s)
+	if err != nil {
+		return nil, versioner, err
+	}
+
+	if utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		// The tests assume that Get/GetList/Watch calls shouldn't fail.
+		// However, 429 error can now be returned if watchcache is under initialization.
+		// To avoid rewriting all tests, we wait for watcache to initialize.
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			return nil, storage.APIObjectVersioner{}, err
+		}
+	}
+	return cacher, versioner, nil
+}
+
 type dummyStorage struct {
 	sync.RWMutex
 	err       error
@@ -222,10 +240,12 @@ func testGetListCacheBypass(t *testing.T, options storage.ListOptions, expectByp
 
 	result := &example.PodList{}
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
+
 	// Inject error to underlying layer and check if cacher is not bypassed.
 	backingStorage.getListFn = func(_ context.Context, key string, opts storage.ListOptions, listObj runtime.Object) error {
 		currentResourceVersion := "42"
@@ -267,9 +287,10 @@ func TestGetListNonRecursiveCacheBypass(t *testing.T) {
 	}
 	result := &example.PodList{}
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	// Inject error to underlying layer and check if cacher is not bypassed.
@@ -301,9 +322,10 @@ func TestGetCacheBypass(t *testing.T) {
 
 	result := &example.Pod{}
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	// Inject error to underlying layer and check if cacher is not bypassed.
@@ -333,9 +355,10 @@ func TestWatchCacheBypass(t *testing.T) {
 	}
 	defer cacher.Stop()
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	_, err = cacher.Watch(context.TODO(), "pod/ns", storage.ListOptions{
@@ -375,6 +398,43 @@ func TestWatchCacheBypass(t *testing.T) {
 	}
 }
 
+func TestTooManyRequestsNotReturned(t *testing.T) {
+	// Ensure that with ResilientWatchCacheInitialization feature disabled, we don't return 429
+	// errors when watchcache is not initialized.
+	featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.ResilientWatchCacheInitialization, false)
+
+	dummyErr := fmt.Errorf("dummy")
+	backingStorage := &dummyStorage{err: dummyErr}
+	cacher, _, err := newTestCacherWithoutSyncing(backingStorage)
+	if err != nil {
+		t.Fatalf("Couldn't create cacher: %v", err)
+	}
+	defer cacher.Stop()
+
+	opts := storage.ListOptions{
+		ResourceVersion: "0",
+		Predicate:       storage.Everything,
+	}
+
+	// Cancel the request so that it doesn't hang forever.
+	listCtx, listCancel := context.WithTimeout(context.Background(), 250*time.Millisecond)
+	defer listCancel()
+
+	result := &example.PodList{}
+	err = cacher.GetList(listCtx, "/pods/ns", opts, result)
+	if err != nil && apierrors.IsTooManyRequests(err) {
+		t.Errorf("Unexpected 429 error without ResilientWatchCacheInitialization feature for List")
+	}
+
+	watchCtx, watchCancel := context.WithTimeout(context.Background(), 250*time.Millisecond)
+	defer watchCancel()
+
+	_, err = cacher.Watch(watchCtx, "/pods/ns", opts)
+	if err != nil && apierrors.IsTooManyRequests(err) {
+		t.Errorf("Unexpected 429 error without ResilientWatchCacheInitialization feature for Watch")
+	}
+}
+
 func TestEmptyWatchEventCache(t *testing.T) {
 	server, etcdStorage := newEtcdTestStorage(t, etcd3testing.PathPrefix())
 	defer server.Terminate(t)
@@ -471,7 +531,7 @@ func TestWatchNotHangingOnStartupFailure(t *testing.T) {
 	// constantly failing lists to the underlying storage.
 	dummyErr := fmt.Errorf("dummy")
 	backingStorage := &dummyStorage{err: dummyErr}
-	cacher, _, err := newTestCacher(backingStorage)
+	cacher, _, err := newTestCacherWithoutSyncing(backingStorage)
 	if err != nil {
 		t.Fatalf("Couldn't create cacher: %v", err)
 	}
@@ -489,8 +549,14 @@ func TestWatchNotHangingOnStartupFailure(t *testing.T) {
 	// Ensure that it terminates when its context is cancelled
 	// (e.g. the request is terminated for whatever reason).
 	_, err = cacher.Watch(ctx, "pods/ns", storage.ListOptions{ResourceVersion: "0"})
-	if err == nil || err.Error() != apierrors.NewServiceUnavailable(context.Canceled.Error()).Error() {
-		t.Errorf("Unexpected error: %#v", err)
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err == nil || err.Error() != apierrors.NewServiceUnavailable(context.Canceled.Error()).Error() {
+			t.Errorf("Unexpected error: %#v", err)
+		}
+	} else {
+		if err == nil || err.Error() != apierrors.NewTooManyRequests("storage is (re)initializing", 1).Error() {
+			t.Errorf("Unexpected error: %#v", err)
+		}
 	}
 }
 
@@ -502,9 +568,10 @@ func TestWatcherNotGoingBackInTime(t *testing.T) {
 	}
 	defer cacher.Stop()
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	// Ensure there is some budget for slowing down processing.
@@ -588,9 +655,10 @@ func TestCacherDontAcceptRequestsStopped(t *testing.T) {
 		t.Fatalf("Couldn't create cacher: %v", err)
 	}
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	w, err := cacher.Watch(context.Background(), "pods/ns", storage.ListOptions{ResourceVersion: "0", Predicate: storage.Everything})
@@ -623,17 +691,32 @@ func TestCacherDontAcceptRequestsStopped(t *testing.T) {
 		IgnoreNotFound:  true,
 		ResourceVersion: "1",
 	}, result)
-	if err == nil {
-		t.Fatalf("Success to create Get: %v", err)
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err == nil {
+			t.Fatalf("Success to create Get: %v", err)
+		}
+	} else {
+		if err != nil {
+			t.Fatalf("Failed to get object: %v:", err)
+		}
 	}
 
 	listResult := &example.PodList{}
 	err = cacher.GetList(context.TODO(), "pods/ns", storage.ListOptions{
 		ResourceVersion: "1",
 		Recursive:       true,
+		Predicate: storage.SelectionPredicate{
+			Limit: 500,
+		},
 	}, listResult)
-	if err == nil {
-		t.Fatalf("Success to create GetList: %v", err)
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err == nil {
+			t.Fatalf("Success to create GetList: %v", err)
+		}
+	} else {
+		if err != nil {
+			t.Fatalf("Failed to list objects: %v", err)
+		}
 	}
 
 	select {
@@ -762,10 +845,12 @@ func TestCacherNoLeakWithMultipleWatchers(t *testing.T) {
 	}
 	defer cacher.Stop()
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
+
 	pred := storage.Everything
 	pred.AllowWatchBookmarks = true
 
@@ -841,9 +926,10 @@ func testCacherSendBookmarkEvents(t *testing.T, allowWatchBookmarks, expectedBoo
 	}
 	defer cacher.Stop()
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 	pred := storage.Everything
 	pred.AllowWatchBookmarks = allowWatchBookmarks
@@ -941,9 +1027,10 @@ func TestCacherSendsMultipleWatchBookmarks(t *testing.T) {
 	// resolution how frequency we recompute.
 	cacher.bookmarkWatchers.bookmarkFrequency = time.Second
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 	pred := storage.Everything
 	pred.AllowWatchBookmarks = true
@@ -1011,9 +1098,10 @@ func TestDispatchingBookmarkEventsWithConcurrentStop(t *testing.T) {
 	}
 	defer cacher.Stop()
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	// Ensure there is some budget for slowing down processing.
@@ -1089,9 +1177,10 @@ func TestBookmarksOnResourceVersionUpdates(t *testing.T) {
 	// Ensure that bookmarks are sent more frequently than every 1m.
 	cacher.bookmarkWatchers = newTimeBucketWatchers(clock.RealClock{}, 2*time.Second)
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	makePod := func(i int) *examplev1.Pod {
@@ -1167,9 +1256,10 @@ func TestStartingResourceVersion(t *testing.T) {
 	}
 	defer cacher.Stop()
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	// Ensure there is some budget for slowing down processing.
@@ -1247,9 +1337,10 @@ func TestDispatchEventWillNotBeBlockedByTimedOutWatcher(t *testing.T) {
 	}
 	defer cacher.Stop()
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	// Ensure there is some budget for slowing down processing.
@@ -1389,9 +1480,10 @@ func TestCachingDeleteEvents(t *testing.T) {
 	}
 	defer cacher.Stop()
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	fooPredicate := storage.SelectionPredicate{
@@ -1471,9 +1563,10 @@ func testCachingObjects(t *testing.T, watchersCount int) {
 	}
 	defer cacher.Stop()
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	dispatchedEvents := []*watchCacheEvent{}
@@ -1567,10 +1660,12 @@ func TestCacheIntervalInvalidationStopsWatch(t *testing.T) {
 	}
 	defer cacher.Stop()
 
-	// Wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
+
 	// Ensure there is enough budget for slow processing since
 	// the entire watch cache is going to be served through the
 	// interval and events won't be popped from the cacheWatcher's
@@ -1754,8 +1849,11 @@ func TestWaitUntilWatchCacheFreshAndForceAllEvents(t *testing.T) {
 				t.Fatalf("Couldn't create cacher: %v", err)
 			}
 			defer cacher.Stop()
-			if err := cacher.ready.wait(context.Background()); err != nil {
-				t.Fatalf("unexpected error waiting for the cache to be ready")
+
+			if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+				if err := cacher.ready.wait(context.Background()); err != nil {
+					t.Fatalf("unexpected error waiting for the cache to be ready")
+				}
 			}
 
 			w, err := cacher.Watch(context.Background(), "pods/ns", scenario.opts)
@@ -1911,9 +2009,10 @@ func TestWatchListIsSynchronisedWhenNoEventsFromStoreReceived(t *testing.T) {
 	require.NoError(t, err, "failed to create cacher")
 	defer cacher.Stop()
 
-	// wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	pred := storage.Everything
@@ -1942,9 +2041,10 @@ func TestForgetWatcher(t *testing.T) {
 	require.NoError(t, err)
 	defer cacher.Stop()
 
-	// wait until cacher is initialized.
-	if err := cacher.ready.wait(context.Background()); err != nil {
-		t.Fatalf("unexpected error waiting for the cache to be ready")
+	if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+		if err := cacher.ready.wait(context.Background()); err != nil {
+			t.Fatalf("unexpected error waiting for the cache to be ready")
+		}
 	}
 
 	assertCacherInternalState := func(expectedWatchersCounter, expectedValueWatchersCounter int) {
@@ -2334,8 +2434,11 @@ func TestGetBookmarkAfterResourceVersionLockedFunc(t *testing.T) {
 			require.NoError(t, err, "couldn't create cacher")
 
 			defer cacher.Stop()
-			if err := cacher.ready.wait(context.Background()); err != nil {
-				t.Fatalf("unexpected error waiting for the cache to be ready")
+
+			if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+				if err := cacher.ready.wait(context.Background()); err != nil {
+					t.Fatalf("unexpected error waiting for the cache to be ready")
+				}
 			}
 
 			cacher.watchCache.UpdateResourceVersion(fmt.Sprintf("%d", scenario.watchCacheResourceVersion))
@@ -2395,8 +2498,11 @@ func TestWatchStreamSeparation(t *testing.T) {
 			featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.SeparateCacheWatchRPC, tc.separateCacheWatchRPC)
 			_, cacher, _, terminate := testSetupWithEtcdServer(t)
 			t.Cleanup(terminate)
-			if err := cacher.ready.wait(context.TODO()); err != nil {
-				t.Fatalf("unexpected error waiting for the cache to be ready")
+
+			if !utilfeature.DefaultFeatureGate.Enabled(features.ResilientWatchCacheInitialization) {
+				if err := cacher.ready.wait(context.TODO()); err != nil {
+					t.Fatalf("unexpected error waiting for the cache to be ready")
+				}
 			}
 
 			getCacherRV := func() uint64 {

staging/src/k8s.io/client-go/tools/cache/reflector_test.go

@@ -697,13 +697,59 @@ func TestBackoffOnTooManyRequests(t *testing.T) {
 	}
 
 	stopCh := make(chan struct{})
-	r.ListAndWatch(stopCh)
+	if err := r.ListAndWatch(stopCh); err != nil {
+		t.Fatal(err)
+	}
 	close(stopCh)
 	if bm.calls != 2 {
 		t.Errorf("unexpected watch backoff calls: %d", bm.calls)
 	}
 }
 
+func TestNoRelistOnTooManyRequests(t *testing.T) {
+	err := apierrors.NewTooManyRequests("too many requests", 1)
+	clock := &clock.RealClock{}
+	bm := &fakeBackoff{clock: clock}
+	listCalls, watchCalls := 0, 0
+
+	lw := &testLW{
+		ListFunc: func(options metav1.ListOptions) (runtime.Object, error) {
+			listCalls++
+			return &v1.PodList{ListMeta: metav1.ListMeta{ResourceVersion: "1"}}, nil
+		},
+		WatchFunc: func(options metav1.ListOptions) (watch.Interface, error) {
+			watchCalls++
+			if watchCalls < 5 {
+				return nil, err
+			}
+			w := watch.NewFake()
+			w.Stop()
+			return w, nil
+		},
+	}
+
+	r := &Reflector{
+		name:              "test-reflector",
+		listerWatcher:     lw,
+		store:             NewFIFO(MetaNamespaceKeyFunc),
+		backoffManager:    bm,
+		clock:             clock,
+		watchErrorHandler: WatchErrorHandler(DefaultWatchErrorHandler),
+	}
+
+	stopCh := make(chan struct{})
+	if err := r.ListAndWatch(stopCh); err != nil {
+		t.Fatal(err)
+	}
+	close(stopCh)
+	if listCalls != 1 {
+		t.Errorf("unexpected list calls: %d", listCalls)
+	}
+	if watchCalls != 5 {
+		t.Errorf("unexpected watch calls: %d", watchCalls)
+	}
+}
+
 func TestRetryInternalError(t *testing.T) {
 	testCases := []struct {
 		name                string