apiserver: allow zero value for the 'nominalConcurrencyShares' field

Kubernetes-commit: 9fd2ab419ad771790d3cb80ea7b8e6828d9ce305

pkg/apis/flowcontrol/bootstrap/default.go

@@ -23,7 +23,7 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apiserver/pkg/authentication/serviceaccount"
 	"k8s.io/apiserver/pkg/authentication/user"
-	"k8s.io/utils/pointer"
+	"k8s.io/utils/ptr"
 )
 
 // The objects that define an apiserver's initial behavior.  The
@@ -90,8 +90,8 @@ var (
 		flowcontrol.PriorityLevelConfigurationSpec{
 			Type: flowcontrol.PriorityLevelEnablementExempt,
 			Exempt: &flowcontrol.ExemptPriorityLevelConfiguration{
-				NominalConcurrencyShares: pointer.Int32(0),
+				NominalConcurrencyShares: ptr.To(int32(0)),
-				LendablePercent:          pointer.Int32(0),
+				LendablePercent:          ptr.To(int32(0)),
 			},
 		},
 	)
@@ -100,8 +100,8 @@ var (
 		flowcontrol.PriorityLevelConfigurationSpec{
 			Type: flowcontrol.PriorityLevelEnablementLimited,
 			Limited: &flowcontrol.LimitedPriorityLevelConfiguration{
-				NominalConcurrencyShares: 5,
+				NominalConcurrencyShares: ptr.To(int32(5)),
-				LendablePercent:          pointer.Int32(0),
+				LendablePercent:          ptr.To(int32(0)),
 				LimitResponse: flowcontrol.LimitResponse{
 					Type: flowcontrol.LimitResponseTypeReject,
 				},
@@ -173,8 +173,8 @@ var (
 		flowcontrol.PriorityLevelConfigurationSpec{
 			Type: flowcontrol.PriorityLevelEnablementLimited,
 			Limited: &flowcontrol.LimitedPriorityLevelConfiguration{
-				NominalConcurrencyShares: 30,
+				NominalConcurrencyShares: ptr.To(int32(30)),
-				LendablePercent:          pointer.Int32(33),
+				LendablePercent:          ptr.To(int32(33)),
 				LimitResponse: flowcontrol.LimitResponse{
 					Type: flowcontrol.LimitResponseTypeQueue,
 					Queuing: &flowcontrol.QueuingConfiguration{
@@ -190,8 +190,8 @@ var (
 		flowcontrol.PriorityLevelConfigurationSpec{
 			Type: flowcontrol.PriorityLevelEnablementLimited,
 			Limited: &flowcontrol.LimitedPriorityLevelConfiguration{
-				NominalConcurrencyShares: 40,
+				NominalConcurrencyShares: ptr.To(int32(40)),
-				LendablePercent:          pointer.Int32(25),
+				LendablePercent:          ptr.To(int32(25)),
 				LimitResponse: flowcontrol.LimitResponse{
 					Type: flowcontrol.LimitResponseTypeQueue,
 					Queuing: &flowcontrol.QueuingConfiguration{
@@ -208,8 +208,8 @@ var (
 		flowcontrol.PriorityLevelConfigurationSpec{
 			Type: flowcontrol.PriorityLevelEnablementLimited,
 			Limited: &flowcontrol.LimitedPriorityLevelConfiguration{
-				NominalConcurrencyShares: 10,
+				NominalConcurrencyShares: ptr.To(int32(10)),
-				LendablePercent:          pointer.Int32(0),
+				LendablePercent:          ptr.To(int32(0)),
 				LimitResponse: flowcontrol.LimitResponse{
 					Type: flowcontrol.LimitResponseTypeQueue,
 					Queuing: &flowcontrol.QueuingConfiguration{
@@ -226,8 +226,8 @@ var (
 		flowcontrol.PriorityLevelConfigurationSpec{
 			Type: flowcontrol.PriorityLevelEnablementLimited,
 			Limited: &flowcontrol.LimitedPriorityLevelConfiguration{
-				NominalConcurrencyShares: 40,
+				NominalConcurrencyShares: ptr.To(int32(40)),
-				LendablePercent:          pointer.Int32(50),
+				LendablePercent:          ptr.To(int32(50)),
 				LimitResponse: flowcontrol.LimitResponse{
 					Type: flowcontrol.LimitResponseTypeQueue,
 					Queuing: &flowcontrol.QueuingConfiguration{
@@ -244,8 +244,8 @@ var (
 		flowcontrol.PriorityLevelConfigurationSpec{
 			Type: flowcontrol.PriorityLevelEnablementLimited,
 			Limited: &flowcontrol.LimitedPriorityLevelConfiguration{
-				NominalConcurrencyShares: 100,
+				NominalConcurrencyShares: ptr.To(int32(100)),
-				LendablePercent:          pointer.Int32(90),
+				LendablePercent:          ptr.To(int32(90)),
 				LimitResponse: flowcontrol.LimitResponse{
 					Type: flowcontrol.LimitResponseTypeQueue,
 					Queuing: &flowcontrol.QueuingConfiguration{
@@ -262,8 +262,8 @@ var (
 		flowcontrol.PriorityLevelConfigurationSpec{
 			Type: flowcontrol.PriorityLevelEnablementLimited,
 			Limited: &flowcontrol.LimitedPriorityLevelConfiguration{
-				NominalConcurrencyShares: 20,
+				NominalConcurrencyShares: ptr.To(int32(20)),
-				LendablePercent:          pointer.Int32(50),
+				LendablePercent:          ptr.To(int32(50)),
 				LimitResponse: flowcontrol.LimitResponse{
 					Type: flowcontrol.LimitResponseTypeQueue,
 					Queuing: &flowcontrol.QueuingConfiguration{

pkg/apis/flowcontrol/bootstrap/default_test.go

@@ -89,7 +89,7 @@ func TestBootstrapPriorityLevelConfigurationWithBorrowing(t *testing.T) {
 			t.Errorf("bootstrap PriorityLevelConfiguration %q is not %q", test.name, flowcontrol.PriorityLevelEnablementLimited)
 			continue
 		}
-		if test.nominalSharesExpected != bootstrapPL.Spec.Limited.NominalConcurrencyShares {
+		if test.nominalSharesExpected != *bootstrapPL.Spec.Limited.NominalConcurrencyShares {
 			t.Errorf("bootstrap PriorityLevelConfiguration %q: expected NominalConcurrencyShares: %d, but got: %d", test.name, test.nominalSharesExpected, bootstrapPL.Spec.Limited.NominalConcurrencyShares)
 		}
 		if test.lendablePercentexpected != *bootstrapPL.Spec.Limited.LendablePercent {

pkg/features/kube_features.go

@@ -251,6 +251,14 @@ const (
 	//
 	// Allow the API server to serve consistent lists from cache
 	ConsistentListFromCache featuregate.Feature = "ConsistentListFromCache"
+
+	// owner: @tkashem
+	// beta: v1.29
+	//
+	// Allow Priority & Fairness in the API server to use a zero value for
+	// the 'nominalConcurrencyShares' field of the 'limited' section of a
+	// priority level.
+	ZeroLimitedNominalConcurrencyShares featuregate.Feature = "ZeroLimitedNominalConcurrencyShares"
 )
 
 func init() {
@@ -315,4 +323,6 @@ var defaultKubernetesFeatureGates = map[featuregate.Feature]featuregate.FeatureS
 	WatchList: {Default: false, PreRelease: featuregate.Alpha},
 
 	ConsistentListFromCache: {Default: false, PreRelease: featuregate.Alpha},
+
+	ZeroLimitedNominalConcurrencyShares: {Default: false, PreRelease: featuregate.Beta},
 }

pkg/server/filters/priority-and-fairness_test.go

@@ -52,6 +52,7 @@ import (
 	"k8s.io/component-base/metrics/testutil"
 	"k8s.io/klog/v2"
 	clocktesting "k8s.io/utils/clock/testing"
+	"k8s.io/utils/ptr"
 
 	"github.com/google/go-cmp/cmp"
 )
@@ -1307,7 +1308,7 @@ func newConfiguration(fsName, plName, user string, concurrency int32, queueLengt
 		Spec: flowcontrol.PriorityLevelConfigurationSpec{
 			Type: flowcontrol.PriorityLevelEnablementLimited,
 			Limited: &flowcontrol.LimitedPriorityLevelConfiguration{
-				NominalConcurrencyShares: concurrency,
+				NominalConcurrencyShares: ptr.To(concurrency),
 				LimitResponse: flowcontrol.LimitResponse{
 					Type:    responseType,
 					Queuing: qcfg,

pkg/util/flowcontrol/apf_controller.go

@@ -702,7 +702,7 @@ func (meal *cfgMeal) digestNewPLsLocked(newPLs []*flowcontrol.PriorityLevelConfi
 			state.quiescing = false
 		}
 		nominalConcurrencyShares, _, _ := plSpecCommons(state.pl)
-		meal.shareSum += float64(nominalConcurrencyShares)
+		meal.shareSum += float64(*nominalConcurrencyShares)
 		meal.haveExemptPL = meal.haveExemptPL || pl.Name == flowcontrol.PriorityLevelConfigurationNameExempt
 		meal.haveCatchAllPL = meal.haveCatchAllPL || pl.Name == flowcontrol.PriorityLevelConfigurationNameCatchAll
 	}
@@ -807,7 +807,7 @@ func (meal *cfgMeal) processOldPLsLocked() {
 		// allocation determined by all the share values in the
 		// regular way.
 		nominalConcurrencyShares, _, _ := plSpecCommons(plState.pl)
-		meal.shareSum += float64(nominalConcurrencyShares)
+		meal.shareSum += float64(*nominalConcurrencyShares)
 		meal.haveExemptPL = meal.haveExemptPL || plName == flowcontrol.PriorityLevelConfigurationNameExempt
 		meal.haveCatchAllPL = meal.haveCatchAllPL || plName == flowcontrol.PriorityLevelConfigurationNameCatchAll
 		meal.newPLStates[plName] = plState
@@ -823,7 +823,7 @@ func (meal *cfgMeal) finishQueueSetReconfigsLocked() {
 		// The use of math.Ceil here means that the results might sum
 		// to a little more than serverConcurrencyLimit but the
 		// difference will be negligible.
-		concurrencyLimit := int(math.Ceil(float64(meal.cfgCtlr.serverConcurrencyLimit) * float64(nominalConcurrencyShares) / meal.shareSum))
+		concurrencyLimit := int(math.Ceil(float64(meal.cfgCtlr.serverConcurrencyLimit) * float64(*nominalConcurrencyShares) / meal.shareSum))
 		var lendableCL, borrowingCL int
 		if lendablePercent != nil {
 			lendableCL = int(math.Round(float64(concurrencyLimit) * float64(*lendablePercent) / 100))
@@ -974,7 +974,7 @@ func (meal *cfgMeal) imaginePL(proto *flowcontrol.PriorityLevelConfiguration) {
 		seatDemandRatioedGauge: seatDemandRatioedGauge,
 	}
 	nominalConcurrencyShares, _, _ := plSpecCommons(proto)
-	meal.shareSum += float64(nominalConcurrencyShares)
+	meal.shareSum += float64(*nominalConcurrencyShares)
 }
 
 // startRequest classifies and, if appropriate, enqueues the request.
@@ -1112,7 +1112,7 @@ func relDiff(x, y float64) float64 {
 }
 
 // plSpecCommons returns the (NominalConcurrencyShares, LendablePercent, BorrowingLimitPercent) of the given priority level config
-func plSpecCommons(pl *flowcontrol.PriorityLevelConfiguration) (int32, *int32, *int32) {
+func plSpecCommons(pl *flowcontrol.PriorityLevelConfiguration) (*int32, *int32, *int32) {
 	if limiter := pl.Spec.Limited; limiter != nil {
 		return limiter.NominalConcurrencyShares, limiter.LendablePercent, limiter.BorrowingLimitPercent
 	}
@@ -1121,5 +1121,5 @@ func plSpecCommons(pl *flowcontrol.PriorityLevelConfiguration) (int32, *int32, *
 	if limiter.NominalConcurrencyShares != nil {
 		nominalConcurrencyShares = *limiter.NominalConcurrencyShares
 	}
-	return nominalConcurrencyShares, limiter.LendablePercent, nil
+	return &nominalConcurrencyShares, limiter.LendablePercent, nil
 }

pkg/util/flowcontrol/apf_filter_test.go

@@ -33,6 +33,7 @@ import (
 	fcrequest "k8s.io/apiserver/pkg/util/flowcontrol/request"
 	"k8s.io/client-go/informers"
 	clientsetfake "k8s.io/client-go/kubernetes/fake"
+	"k8s.io/utils/ptr"
 )
 
 // TestQueueWaitTimeLatencyTracker tests the queue wait times recorded by the P&F latency tracker
@@ -80,7 +81,7 @@ func TestQueueWaitTimeLatencyTracker(t *testing.T) {
 		Spec: flowcontrol.PriorityLevelConfigurationSpec{
 			Type: flowcontrol.PriorityLevelEnablementLimited,
 			Limited: &flowcontrol.LimitedPriorityLevelConfiguration{
-				NominalConcurrencyShares: 100,
+				NominalConcurrencyShares: ptr.To(int32(100)),
 				LendablePercent:          &lendable,
 				BorrowingLimitPercent:    &borrowingLimit,
 				LimitResponse: flowcontrol.LimitResponse{

pkg/util/flowcontrol/borrowing_test.go

@@ -36,6 +36,7 @@ import (
 	fcrequest "k8s.io/apiserver/pkg/util/flowcontrol/request"
 	"k8s.io/client-go/informers"
 	clientsetfake "k8s.io/client-go/kubernetes/fake"
+	"k8s.io/utils/ptr"
 )
 
 type borrowingTestConstraints struct {
@@ -115,7 +116,7 @@ func TestBorrowing(t *testing.T) {
 					Spec: flowcontrol.PriorityLevelConfigurationSpec{
 						Type: flowcontrol.PriorityLevelEnablementLimited,
 						Limited: &flowcontrol.LimitedPriorityLevelConfiguration{
-							NominalConcurrencyShares: 100,
+							NominalConcurrencyShares: ptr.To(int32(100)),
 							LendablePercent:          &testCase.constraints[flow].lendable,
 							BorrowingLimitPercent:    &testCase.constraints[flow].borrowing,
 							LimitResponse: flowcontrol.LimitResponse{

pkg/util/flowcontrol/controller_test.go

@@ -41,6 +41,7 @@ import (
 	fcclient "k8s.io/client-go/kubernetes/typed/flowcontrol/v1"
 	"k8s.io/klog/v2"
 	"k8s.io/utils/clock"
+	"k8s.io/utils/ptr"
 )
 
 // Some tests print a lot of debug logs which slows down tests considerably,
@@ -357,7 +358,7 @@ func TestAPFControllerWithGracefulShutdown(t *testing.T) {
 		Spec: flowcontrol.PriorityLevelConfigurationSpec{
 			Type: flowcontrol.PriorityLevelEnablementLimited,
 			Limited: &flowcontrol.LimitedPriorityLevelConfiguration{
-				NominalConcurrencyShares: 10,
+				NominalConcurrencyShares: ptr.To(int32(10)),
 				LimitResponse: flowcontrol.LimitResponse{
 					Type: flowcontrol.LimitResponseTypeReject,
 				},

pkg/util/flowcontrol/gen_test.go

@@ -23,6 +23,7 @@ import (
 	"testing"
 
 	"k8s.io/utils/clock"
+	"k8s.io/utils/ptr"
 
 	flowcontrol "k8s.io/api/flowcontrol/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -47,7 +48,7 @@ func genPL(rng *rand.Rand, name string) *flowcontrol.PriorityLevelConfiguration
 		Spec: flowcontrol.PriorityLevelConfigurationSpec{
 			Type: flowcontrol.PriorityLevelEnablementLimited,
 			Limited: &flowcontrol.LimitedPriorityLevelConfiguration{
-				NominalConcurrencyShares: rng.Int31n(100) + 1,
+				NominalConcurrencyShares: ptr.To(int32(rng.Int31n(100) + 1)),
 				LimitResponse: flowcontrol.LimitResponse{
 					Type: flowcontrol.LimitResponseTypeReject}}}}
 	if rng.Float32() < 0.95 {

pkg/util/flowcontrol/max_seats_test.go

@@ -27,6 +27,7 @@ import (
 	"k8s.io/apiserver/pkg/util/flowcontrol/metrics"
 	"k8s.io/client-go/informers"
 	clientsetfake "k8s.io/client-go/kubernetes/fake"
+	"k8s.io/utils/ptr"
 )
 
 // Test_GetMaxSeats tests max seats retrieved from MaxSeatsTracker
@@ -120,7 +121,7 @@ func Test_GetMaxSeats(t *testing.T) {
 				Spec: flowcontrolv1.PriorityLevelConfigurationSpec{
 					Type: flowcontrolv1.PriorityLevelEnablementLimited,
 					Limited: &flowcontrolv1.LimitedPriorityLevelConfiguration{
-						NominalConcurrencyShares: 10000,
+						NominalConcurrencyShares: ptr.To(int32(10000)),
 						LimitResponse: flowcontrolv1.LimitResponse{
 							Queuing: &flowcontrolv1.QueuingConfiguration{
 								HandSize: testcase.handSize,