Refactor and clean up the code

test/integration/apiserver/flowcontrol/concurrency_util_test.go

@@ -81,6 +81,72 @@ func setupWithAuthorizer(t testing.TB, maxReadonlyRequestsInFlight, maxMutatingR
 	return kubeConfig, tearDownFn
 }
 
+type SumAndCount struct {
+	Sum   float64
+	Count int
+}
+
+type plMetrics struct {
+	execSeconds    SumAndCount
+	seatUtil       SumAndCount
+	availableSeats int
+}
+
+// metricSnapshot maps from a priority level label to
+// a plMetrics struct containing APF metrics of interest
+type metricSnapshot map[string]plMetrics
+
+// Client request latency measurement
+type clientLatencyMeasurement struct {
+	SumAndCount
+	SumSq float64 // latency sum of squares
+	Mu    sync.Mutex
+}
+
+func (clm *clientLatencyMeasurement) reset() {
+	clm.Mu.Lock()
+	clm.Sum = 0
+	clm.Count = 0
+	clm.SumSq = 0
+	clm.Mu.Unlock()
+}
+
+func (clm *clientLatencyMeasurement) update(duration float64) {
+	clm.Mu.Lock()
+	clm.Count += 1
+	clm.Sum += duration
+	clm.SumSq += duration * duration
+	clm.Mu.Unlock()
+}
+
+func (clm *clientLatencyMeasurement) getStats() clientLatencyStats {
+	mean := clm.Sum / float64(clm.Count)
+	ss := clm.SumSq - mean*clm.Sum // reduced from ss := sumsq - 2*mean*sum + float64(count)*mean*mean
+	stdDev := math.Sqrt(ss / float64(clm.Count))
+	cv := stdDev / mean
+	return clientLatencyStats{mean: mean, stdDev: stdDev, cv: cv}
+}
+
+type clientLatencyStats struct {
+	mean   float64 // latency average
+	stdDev float64 // latency standard deviation
+	cv     float64 // latency coefficient of variation
+}
+
+type plMetricAvg struct {
+	reqExecution float64 // average request execution time
+	seatUtil     float64 // average seat utilization
+}
+
+func intervalMetricAvg(snapshots map[string]metricSnapshot, t0 string, t1 string, plLabel string) plMetricAvg {
+	plmT0 := snapshots[t0][plLabel]
+	plmT1 := snapshots[t1][plLabel]
+	return plMetricAvg{
+		reqExecution: (plmT1.execSeconds.Sum - plmT0.execSeconds.Sum) / float64(plmT1.execSeconds.Count-plmT0.execSeconds.Count),
+		seatUtil:     (plmT1.seatUtil.Sum - plmT0.seatUtil.Sum) / float64(plmT1.seatUtil.Count-plmT0.seatUtil.Count),
+	}
+}
+
 // This integration test checks the client-side expected concurrency and the server-side observed concurrency
 // to make sure that they are close within a small error bound and that the priority levels are isolated.
 // This test differs from TestPriorityLevelIsolation since TestPriorityLevelIsolation checks throughput instead
@@ -117,65 +183,42 @@ func TestConcurrencyIsolation(t *testing.T) {
 	queueLength := 50
 	concurrencyShares := 100
 
-	priorityLevelNoxu1, _, err := createPriorityLevelAndBindingFlowSchemaForUser(
+	plNoxu1, _, err := createPriorityLevelAndBindingFlowSchemaForUser(
 		loopbackClient, "noxu1", concurrencyShares, queueLength)
 	if err != nil {
 		t.Error(err)
 	}
-	priorityLevelNoxu2, _, err := createPriorityLevelAndBindingFlowSchemaForUser(
+	plNoxu2, _, err := createPriorityLevelAndBindingFlowSchemaForUser(
 		loopbackClient, "noxu2", concurrencyShares, queueLength)
 	if err != nil {
 		t.Error(err)
 	}
-	availableSeats, err := getAvailableSeatsOfPriorityLevel(loopbackClient)
-	if err != nil {
-		t.Error(err)
-	}
-
-	t.Logf("noxu1 priority level concurrency limit: %v", availableSeats[priorityLevelNoxu1.Name])
-	t.Logf("noxu2 priority level concurrency limit: %v", availableSeats[priorityLevelNoxu2.Name])
-	if (availableSeats[priorityLevelNoxu1.Name] <= 4) || (availableSeats[priorityLevelNoxu2.Name] <= 4) {
-		t.Errorf("The number of available seats for test client priority levels are too small: (%v, %v). Expecting a number > 4",
-			availableSeats[priorityLevelNoxu1.Name], availableSeats[priorityLevelNoxu2.Name])
-	}
 
 	stopCh := make(chan struct{})
 	wg := sync.WaitGroup{}
 
 	// "elephant"
 	noxu1NumGoroutines := 5 + queueLength
-	var noxu1ClientRequestLatencySum float64
+	var noxu1LatMeasure clientLatencyMeasurement
-	var noxu1ClientRequestLatencySumSq float64
+	wg.Add(noxu1NumGoroutines)
-	var noxu1ClientRequestLatencyCount int32
+	streamRequests(noxu1NumGoroutines, func() {
-	var noxu1Mutex sync.Mutex
-	streamRequestsWithIndex(noxu1NumGoroutines, func(idx int) {
 		start := time.Now()
 		_, err := noxu1Client.CoreV1().Namespaces().Get(context.Background(), "default", metav1.GetOptions{})
 		duration := time.Since(start).Seconds()
-		noxu1Mutex.Lock()
+		noxu1LatMeasure.update(duration)
-		noxu1ClientRequestLatencyCount += 1
-		noxu1ClientRequestLatencySum += duration
-		noxu1ClientRequestLatencySumSq += duration * duration
-		noxu1Mutex.Unlock()
 		if err != nil {
 			t.Error(err)
 		}
 	}, &wg, stopCh)
 	// "mouse"
 	noxu2NumGoroutines := 3
-	var noxu2ClientRequestLatencySum float64
+	var noxu2LatMeasure clientLatencyMeasurement
-	var noxu2ClientRequestLatencySumSq float64
+	wg.Add(noxu2NumGoroutines)
-	var noxu2ClientRequestLatencyCount int32
+	streamRequests(noxu2NumGoroutines, func() {
-	var noxu2Mutex sync.Mutex
-	streamRequestsWithIndex(noxu2NumGoroutines, func(idx int) {
 		start := time.Now()
 		_, err := noxu2Client.CoreV1().Namespaces().Get(context.Background(), "default", metav1.GetOptions{})
 		duration := time.Since(start).Seconds()
-		noxu2Mutex.Lock()
+		noxu2LatMeasure.update(duration)
-		noxu2ClientRequestLatencyCount += 1
-		noxu2ClientRequestLatencySum += duration
-		noxu2ClientRequestLatencySumSq += duration * duration
-		noxu2Mutex.Unlock()
 		if err != nil {
 			t.Error(err)
 		}
@@ -184,97 +227,101 @@ func TestConcurrencyIsolation(t *testing.T) {
 	// Warm up
 	time.Sleep(testWarmUpTime)
 
-	// Reset counters
+	noxu1LatMeasure.reset()
-	noxu1Mutex.Lock()
+	noxu2LatMeasure.reset()
-	noxu1ClientRequestLatencyCount = 0
+	// Snapshots maps from a time label to a metricSnapshot
-	noxu1ClientRequestLatencySum = 0
+	snapshots := make(map[string]metricSnapshot)
-	noxu1ClientRequestLatencySumSq = 0
+	snapshots["t0"], err = getRequestMetricsSnapshot(loopbackClient)
-	noxu1Mutex.Unlock()
-	noxu2Mutex.Lock()
-	noxu2ClientRequestLatencyCount = 0
-	noxu2ClientRequestLatencySum = 0
-	noxu2ClientRequestLatencySumSq = 0
-	noxu2Mutex.Unlock()
-	earlierRequestExecutionSecondsSum, earlierRequestExecutionSecondsCount, earlierPLSeatUtilSum, earlierPLSeatUtilCount, err := getRequestExecutionMetrics(loopbackClient)
 	if err != nil {
 		t.Error(err)
 	}
 	time.Sleep(testTime) // after warming up, the test enters a steady state
-	laterRequestExecutionSecondsSum, laterRequestExecutionSecondsCount, laterPLSeatUtilSum, laterPLSeatUtilCount, err := getRequestExecutionMetrics(loopbackClient)
+	snapshots["t1"], err = getRequestMetricsSnapshot(loopbackClient)
 	if err != nil {
 		t.Error(err)
 	}
-	if (earlierPLSeatUtilCount[priorityLevelNoxu1.Name] >= laterPLSeatUtilCount[priorityLevelNoxu1.Name]) || (earlierPLSeatUtilCount[priorityLevelNoxu2.Name] >= laterPLSeatUtilCount[priorityLevelNoxu2.Name]) {
-		t.Errorf("PLSeatUtilCount check failed: noxu1 earlier count %v, later count %v; noxu2 earlier count %v, later count %v",
-			earlierPLSeatUtilCount[priorityLevelNoxu1.Name], laterPLSeatUtilCount[priorityLevelNoxu1.Name], earlierPLSeatUtilCount[priorityLevelNoxu2.Name], laterPLSeatUtilCount[priorityLevelNoxu2.Name])
-	}
 	close(stopCh)
 
-	noxu1RequestExecutionSecondsAvg := (laterRequestExecutionSecondsSum[priorityLevelNoxu1.Name] - earlierRequestExecutionSecondsSum[priorityLevelNoxu1.Name]) / float64(laterRequestExecutionSecondsCount[priorityLevelNoxu1.Name]-earlierRequestExecutionSecondsCount[priorityLevelNoxu1.Name])
+	// Check the assumptions of the test
-	noxu2RequestExecutionSecondsAvg := (laterRequestExecutionSecondsSum[priorityLevelNoxu2.Name] - earlierRequestExecutionSecondsSum[priorityLevelNoxu2.Name]) / float64(laterRequestExecutionSecondsCount[priorityLevelNoxu2.Name]-earlierRequestExecutionSecondsCount[priorityLevelNoxu2.Name])
+	noxu1T0 := snapshots["t0"][plNoxu1.Name]
-	noxu1PLSeatUtilAvg := (laterPLSeatUtilSum[priorityLevelNoxu1.Name] - earlierPLSeatUtilSum[priorityLevelNoxu1.Name]) / float64(laterPLSeatUtilCount[priorityLevelNoxu1.Name]-earlierPLSeatUtilCount[priorityLevelNoxu1.Name])
+	noxu1T1 := snapshots["t1"][plNoxu1.Name]
-	noxu2PLSeatUtilAvg := (laterPLSeatUtilSum[priorityLevelNoxu2.Name] - earlierPLSeatUtilSum[priorityLevelNoxu2.Name]) / float64(laterPLSeatUtilCount[priorityLevelNoxu2.Name]-earlierPLSeatUtilCount[priorityLevelNoxu2.Name])
+	noxu2T0 := snapshots["t0"][plNoxu2.Name]
-	t.Logf("\nnoxu1RequestExecutionSecondsAvg %v\nnoxu2RequestExecutionSecondsAvg %v", noxu1RequestExecutionSecondsAvg, noxu2RequestExecutionSecondsAvg)
+	noxu2T1 := snapshots["t1"][plNoxu2.Name]
-	t.Logf("\nnoxu1PLSeatUtilAvg %v\nnoxu2PLSeatUtilAvg %v", noxu1PLSeatUtilAvg, noxu2PLSeatUtilAvg)
+	if noxu1T0.seatUtil.Count >= noxu1T1.seatUtil.Count || noxu2T0.seatUtil.Count >= noxu2T1.seatUtil.Count {
-
+		t.Errorf("SeatUtilCount check failed: noxu1 t0 count %d, t1 count %d; noxu2 t0 count %d, t1 count %d",
-	wg.Wait() // wait till the client goroutines finish before computing the statistics
+			noxu1T0.seatUtil.Count, noxu1T1.seatUtil.Count, noxu2T0.seatUtil.Count, noxu2T1.seatUtil.Count)
-	noxu1ClientRequestLatencySecondsAvg, noxu1ClientRequestLatencySecondsSdev := computeClientRequestLatencyStats(noxu1ClientRequestLatencyCount, noxu1ClientRequestLatencySum, noxu1ClientRequestLatencySumSq)
+	}
-	noxu2ClientRequestLatencySecondsAvg, noxu2ClientRequestLatencySecondsSdev := computeClientRequestLatencyStats(noxu2ClientRequestLatencyCount, noxu2ClientRequestLatencySum, noxu2ClientRequestLatencySumSq)
+	t.Logf("noxu1 priority level concurrency limit: %d", noxu1T0.availableSeats)
-	t.Logf("\nnoxu1ClientRequestLatencyCount %v\nnoxu2ClientRequestLatencyCount %v", noxu1ClientRequestLatencyCount, noxu2ClientRequestLatencyCount)
+	t.Logf("noxu2 priority level concurrency limit: %d", noxu2T0.availableSeats)
-	t.Logf("\nnoxu1ClientRequestLatencySecondsAvg %v\nnoxu2ClientRequestLatencySecondsAvg %v", noxu1ClientRequestLatencySecondsAvg, noxu2ClientRequestLatencySecondsAvg)
+	if (noxu1T0.availableSeats != noxu1T1.availableSeats) || (noxu2T0.availableSeats != noxu2T1.availableSeats) {
-	t.Logf("\nnoxu1ClientRequestLatencySecondsSdev %v\nnoxu2ClientRequestLatencySecondsSdev %v", noxu1ClientRequestLatencySecondsSdev, noxu2ClientRequestLatencySecondsSdev)
+		t.Errorf("The number of available seats changed: noxu1 (%d, %d) noxu2 (%d, %d)",
-	allDispatchedReqCounts, rejectedReqCounts, err := getRequestCountOfPriorityLevel(loopbackClient)
+			noxu1T0.availableSeats, noxu1T1.availableSeats, noxu2T0.availableSeats, noxu2T1.availableSeats)
+	}
+	if (noxu1T0.availableSeats <= 4) || (noxu2T0.availableSeats <= 4) {
+		t.Errorf("The number of available seats for test client priority levels are too small: (%d, %d). Expecting a number > 4",
+			noxu1T0.availableSeats, noxu2T0.availableSeats)
+	}
+	// No reuqests should be rejected under normal situations
+	_, rejectedReqCounts, err := getRequestCountOfPriorityLevel(loopbackClient)
 	if err != nil {
 		t.Error(err)
 	}
-	t.Logf("\nnoxu1APFRequestCount %v\nnoxu2APFRequestCount %v", allDispatchedReqCounts[priorityLevelNoxu1.Name], allDispatchedReqCounts[priorityLevelNoxu2.Name])
+	if rejectedReqCounts[plNoxu1.Name] > 0 {
-	if rejectedReqCounts[priorityLevelNoxu1.Name] > 0 {
+		t.Errorf(`%d requests from the "elephant" stream were rejected unexpectedly`, rejectedReqCounts[plNoxu1.Name])
-		t.Errorf(`%v requests from the "elephant" stream were rejected unexpectedly`, rejectedReqCounts[priorityLevelNoxu2.Name])
 	}
-	if rejectedReqCounts[priorityLevelNoxu2.Name] > 0 {
+	if rejectedReqCounts[plNoxu2.Name] > 0 {
-		t.Errorf(`%v requests from the "mouse" stream were rejected unexpectedly`, rejectedReqCounts[priorityLevelNoxu2.Name])
+		t.Errorf(`%d requests from the "mouse" stream were rejected unexpectedly`, rejectedReqCounts[plNoxu2.Name])
 	}
 
+	// Calculate APF server side metric averages during the test interval
+	noxu1Avg := intervalMetricAvg(snapshots, "t0", "t1", plNoxu1.Name)
+	noxu2Avg := intervalMetricAvg(snapshots, "t0", "t1", plNoxu2.Name)
+	t.Logf("\nnoxu1 avg request execution time %v\nnoxu2 avg request execution time %v", noxu1Avg.reqExecution, noxu2Avg.reqExecution)
+	t.Logf("\nnoxu1 avg seat utilization %v\nnoxu2 avg seat utilization %v", noxu1Avg.seatUtil, noxu2Avg.seatUtil)
+
+	// Wait till the client goroutines finish before computing the client side request latency statistics
+	wg.Wait()
+	noxu1LatStats := noxu1LatMeasure.getStats()
+	noxu2LatStats := noxu2LatMeasure.getStats()
+	t.Logf("noxu1 client request count %d duration mean %v stddev %v cv %v", noxu1LatMeasure.Count, noxu1LatStats.mean, noxu1LatStats.stdDev, noxu1LatStats.cv)
+	t.Logf("noxu2 client request count %d duration mean %v stddev %v cv %v", noxu2LatMeasure.Count, noxu2LatStats.mean, noxu2LatStats.stdDev, noxu2LatStats.cv)
+
 	// Calculate server-side observed concurrency
-	noxu1ObservedConcurrency := noxu1PLSeatUtilAvg * float64(availableSeats[priorityLevelNoxu1.Name])
+	noxu1ObservedConcurrency := noxu1Avg.seatUtil * float64(noxu1T0.availableSeats)
-	noxu2ObservedConcurrency := noxu2PLSeatUtilAvg * float64(availableSeats[priorityLevelNoxu2.Name])
+	noxu2ObservedConcurrency := noxu2Avg.seatUtil * float64(noxu2T0.availableSeats)
 	// Expected concurrency is derived from equal throughput assumption on both the client-side and the server-side
 	// Expected concurrency computed can sometimes be larger than the number of available seats. We use the number of available seats as an upper bound
-	noxu1ExpectedConcurrency := math.Min(float64(noxu1NumGoroutines)*noxu1RequestExecutionSecondsAvg/noxu1ClientRequestLatencySecondsAvg, float64(availableSeats[priorityLevelNoxu1.Name]))
+	noxu1ExpectedConcurrency := float64(noxu1NumGoroutines) * noxu1Avg.reqExecution / noxu1LatStats.mean
-	noxu2ExpectedConcurrency := math.Min(float64(noxu2NumGoroutines)*noxu2RequestExecutionSecondsAvg/noxu2ClientRequestLatencySecondsAvg, float64(availableSeats[priorityLevelNoxu2.Name]))
+	noxu2ExpectedConcurrency := float64(noxu2NumGoroutines) * noxu2Avg.reqExecution / noxu2LatStats.mean
 	t.Logf("Concurrency of noxu1:noxu2 - expected (%v:%v), observed (%v:%v)", noxu1ExpectedConcurrency, noxu2ExpectedConcurrency, noxu1ObservedConcurrency, noxu2ObservedConcurrency)
 	// Calculate the tolerable error margin and perform the final check
-	margin := 2 * math.Min(noxu1ClientRequestLatencySecondsSdev/noxu1ClientRequestLatencySecondsAvg, noxu2ClientRequestLatencySecondsSdev/noxu2ClientRequestLatencySecondsAvg)
+	margin := 2 * math.Min(noxu1LatStats.cv, noxu2LatStats.cv)
-	t.Logf("\nnoxu1Margin %v\nnoxu2Margin %v", noxu1ClientRequestLatencySecondsSdev/noxu1ClientRequestLatencySecondsAvg, noxu2ClientRequestLatencySecondsSdev/noxu2ClientRequestLatencySecondsAvg)
 	t.Logf("Error margin is %v", margin)
 
 	isConcurrencyExpected := func(name string, observed float64, expected float64) bool {
 		t.Logf("%v relative error is %v", name, math.Abs(expected-observed)/expected)
 		return math.Abs(expected-observed)/expected <= margin
 	}
-	if !isConcurrencyExpected(priorityLevelNoxu1.Name, noxu1ObservedConcurrency, noxu1ExpectedConcurrency) {
+	if !isConcurrencyExpected(plNoxu1.Name, noxu1ObservedConcurrency, noxu1ExpectedConcurrency) {
 		t.Errorf("Concurrency observed by noxu1 is off. Expected: %v, observed: %v", noxu1ExpectedConcurrency, noxu1ObservedConcurrency)
 	}
-	if !isConcurrencyExpected(priorityLevelNoxu2.Name, noxu2ObservedConcurrency, noxu2ExpectedConcurrency) {
+	if !isConcurrencyExpected(plNoxu2.Name, noxu2ObservedConcurrency, noxu2ExpectedConcurrency) {
 		t.Errorf("Concurrency observed by noxu2 is off. Expected: %v, observed: %v", noxu2ExpectedConcurrency, noxu2ObservedConcurrency)
 	}
 
 	// Check server-side APF measurements
-	if math.Abs(1-noxu1PLSeatUtilAvg) > 0.05 {
+	// For the elephant noxu1, the avg seat utilization should be close to 1.0
-		t.Errorf("noxu1PLSeatUtilAvg=%v is too far from expected=1.0", noxu1PLSeatUtilAvg)
+	if math.Abs(1-noxu1Avg.seatUtil) > 0.05 {
+		t.Errorf("noxu1PLSeatUtilAvg=%v is too far from expected=1.0", noxu1Avg.seatUtil)
 	}
+	// For the mouse noxu2, the observed concurrency should be close to the number of goroutines it uses
 	if math.Abs(1-noxu2ObservedConcurrency/float64(noxu2NumGoroutines)) > 0.05 {
-		t.Errorf("noxu2ObservedConcurrency=%v is too far from noxu2NumGoroutines=%v", noxu2ObservedConcurrency, noxu2NumGoroutines)
+		t.Errorf("noxu2ObservedConcurrency=%v is too far from noxu2NumGoroutines=%d", noxu2ObservedConcurrency, noxu2NumGoroutines)
 	}
 }
 
-func computeClientRequestLatencyStats(count int32, sum, sumsq float64) (float64, float64) {
+func getRequestMetricsSnapshot(c clientset.Interface) (metricSnapshot, error) {
-	mean := sum / float64(count)
-	ss := sumsq - mean*sum // reduced from ss := sumsq - 2*mean*sum + float64(count)*mean*mean
-	return mean, math.Sqrt(ss / float64(count))
-}
 
-func getAvailableSeatsOfPriorityLevel(c clientset.Interface) (map[string]int, error) {
 	resp, err := getMetrics(c)
 	if err != nil {
 		return nil, err
@@ -286,85 +333,40 @@ func getAvailableSeatsOfPriorityLevel(c clientset.Interface) (map[string]int, er
 		Opts: &expfmt.DecodeOptions{},
 	}
 
-	concurrency := make(map[string]int)
+	snapshot := metricSnapshot{}
+
 	for {
 		var v model.Vector
 		if err := decoder.Decode(&v); err != nil {
 			if err == io.EOF {
 				// Expected loop termination condition.
-				return concurrency, nil
+				return snapshot, nil
 			}
 			return nil, fmt.Errorf("failed decoding metrics: %v", err)
 		}
 		for _, metric := range v {
-			switch name := string(metric.Metric[model.MetricNameLabel]); name {
+			plLabel := string(metric.Metric[labelPriorityLevel])
-			case requestConcurrencyLimitMetricsName:
+			entry := plMetrics{}
-				concurrency[string(metric.Metric[labelPriorityLevel])] = int(metric.Value)
+			if v, ok := snapshot[plLabel]; ok {
+				entry = v
 			}
-		}
-	}
-}
-
-func getRequestExecutionMetrics(c clientset.Interface) (map[string]float64, map[string]int, map[string]float64, map[string]int, error) {
-
-	resp, err := getMetrics(c)
-	if err != nil {
-		return nil, nil, nil, nil, err
-	}
-
-	dec := expfmt.NewDecoder(strings.NewReader(string(resp)), expfmt.FmtText)
-	decoder := expfmt.SampleDecoder{
-		Dec:  dec,
-		Opts: &expfmt.DecodeOptions{},
-	}
-
-	RequestExecutionSecondsSum := make(map[string]float64)
-	RequestExecutionSecondsCount := make(map[string]int)
-	PLSeatUtilSum := make(map[string]float64)
-	PLSeatUtilCount := make(map[string]int)
-
-	for {
-		var v model.Vector
-		if err := decoder.Decode(&v); err != nil {
-			if err == io.EOF {
-				// Expected loop termination condition.
-				return RequestExecutionSecondsSum, RequestExecutionSecondsCount,
-					PLSeatUtilSum, PLSeatUtilCount, nil
-			}
-			return nil, nil, nil, nil, fmt.Errorf("failed decoding metrics: %v", err)
-		}
-		for _, metric := range v {
 			switch name := string(metric.Metric[model.MetricNameLabel]); name {
 			case requestExecutionSecondsSumName:
-				RequestExecutionSecondsSum[string(metric.Metric[labelPriorityLevel])] = float64(metric.Value)
+				entry.execSeconds.Sum = float64(metric.Value)
 			case requestExecutionSecondsCountName:
-				RequestExecutionSecondsCount[string(metric.Metric[labelPriorityLevel])] = int(metric.Value)
+				entry.execSeconds.Count = int(metric.Value)
 			case priorityLevelSeatUtilSumName:
-				PLSeatUtilSum[string(metric.Metric[labelPriorityLevel])] = float64(metric.Value)
+				entry.seatUtil.Sum = float64(metric.Value)
 			case priorityLevelSeatUtilCountName:
-				PLSeatUtilCount[string(metric.Metric[labelPriorityLevel])] = int(metric.Value)
+				entry.seatUtil.Count = int(metric.Value)
+			case requestConcurrencyLimitMetricsName:
+				entry.availableSeats = int(metric.Value)
 			}
+			snapshot[plLabel] = entry
 		}
 	}
 }
 
-func streamRequestsWithIndex(parallel int, request func(idx int), wg *sync.WaitGroup, stopCh <-chan struct{}) {
-	wg.Add(parallel)
-	for i := 0; i < parallel; i++ {
-		go func(idx int) {
-			defer wg.Done()
-			for {
-				select {
-				case <-stopCh:
-					return
-				default:
-					request(idx)
-				}
-			}
-		}(i)
-	}
-}
-
 // Webhook authorizer code copied from staging/src/k8s.io/apiserver/plugin/pkg/authenticator/token/webhook/webhook_v1_test.go with minor changes
 // V1Service mocks a remote service.
 type V1Service interface {
@@ -454,14 +456,12 @@ func NewV1TestServer(s V1Service, cert, key, caCert []byte) (*httptest.Server, e
 type mockV1Service struct {
 	allow      bool
 	statusCode int
-	called     int
 }
 
 func (m *mockV1Service) Review(r *authorizationv1.SubjectAccessReview) {
 	if r.Spec.User == "noxu1" || r.Spec.User == "noxu2" {
 		time.Sleep(fakeworkDuration) // simulate fake work with sleep
 	}
-	m.called++
 	r.Status.Allowed = m.allow
 }
 func (m *mockV1Service) HTTPStatusCode() int { return m.statusCode }