7681c284f5
Instead discard metric values for pods that are unready and have never been ready (they may report misleading values, the original reason for introducing scale up forbidden window). Use per pod metric when pod is: - Ready, or - Not ready but creation timestamp and last readiness change are more than 10s apart. In the latter case we asume the pod was ready but later became unready. We want to use metrics for such pods because sometimes such pods are unready because they were getting too much load.
407 lines
16 KiB
Go
407 lines
16 KiB
Go
/*
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Copyright 2016 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package podautoscaler
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import (
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"fmt"
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"math"
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"time"
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autoscaling "k8s.io/api/autoscaling/v2beta1"
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"k8s.io/api/core/v1"
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metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
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"k8s.io/apimachinery/pkg/labels"
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"k8s.io/apimachinery/pkg/util/sets"
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v1coreclient "k8s.io/client-go/kubernetes/typed/core/v1"
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podutil "k8s.io/kubernetes/pkg/api/v1/pod"
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metricsclient "k8s.io/kubernetes/pkg/controller/podautoscaler/metrics"
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)
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const (
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// defaultTestingTolerance is default value for calculating when to
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// scale up/scale down.
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defaultTestingTolerance = 0.1
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// Pod begins existence as unready. If pod is unready and timestamp of last pod readiness change is
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// less than maxDelayOfInitialReadinessStatus after pod start we assume it has never been ready.
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maxDelayOfInitialReadinessStatus = 10 * time.Second
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)
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type ReplicaCalculator struct {
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metricsClient metricsclient.MetricsClient
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podsGetter v1coreclient.PodsGetter
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tolerance float64
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}
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func NewReplicaCalculator(metricsClient metricsclient.MetricsClient, podsGetter v1coreclient.PodsGetter, tolerance float64) *ReplicaCalculator {
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return &ReplicaCalculator{
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metricsClient: metricsClient,
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podsGetter: podsGetter,
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tolerance: tolerance,
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}
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}
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// GetResourceReplicas calculates the desired replica count based on a target resource utilization percentage
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// of the given resource for pods matching the given selector in the given namespace, and the current replica count
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func (c *ReplicaCalculator) GetResourceReplicas(currentReplicas int32, targetUtilization int32, resource v1.ResourceName, namespace string, selector labels.Selector) (replicaCount int32, utilization int32, rawUtilization int64, timestamp time.Time, err error) {
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metrics, timestamp, err := c.metricsClient.GetResourceMetric(resource, namespace, selector)
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if err != nil {
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return 0, 0, 0, time.Time{}, fmt.Errorf("unable to get metrics for resource %s: %v", resource, err)
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}
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podList, err := c.podsGetter.Pods(namespace).List(metav1.ListOptions{LabelSelector: selector.String()})
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if err != nil {
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return 0, 0, 0, time.Time{}, fmt.Errorf("unable to get pods while calculating replica count: %v", err)
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}
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itemsLen := len(podList.Items)
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if itemsLen == 0 {
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return 0, 0, 0, time.Time{}, fmt.Errorf("no pods returned by selector while calculating replica count")
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}
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requests := make(map[string]int64, itemsLen)
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readyPodCount := 0
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unreadyPods := sets.NewString()
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missingPods := sets.NewString()
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for _, pod := range podList.Items {
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podSum := int64(0)
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for _, container := range pod.Spec.Containers {
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if containerRequest, ok := container.Resources.Requests[resource]; ok {
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podSum += containerRequest.MilliValue()
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} else {
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return 0, 0, 0, time.Time{}, fmt.Errorf("missing request for %s on container %s in pod %s/%s", resource, container.Name, namespace, pod.Name)
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}
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}
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requests[pod.Name] = podSum
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if pod.Status.Phase != v1.PodRunning || !podutil.IsPodReady(&pod) {
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// save this pod name for later, but pretend it doesn't exist for now
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if pod.Status.Phase != v1.PodFailed {
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// Failed pods should not be counted as unready pods as they will
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// not become running anymore.
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unreadyPods.Insert(pod.Name)
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}
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delete(metrics, pod.Name)
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continue
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}
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if _, found := metrics[pod.Name]; !found {
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// save this pod name for later, but pretend it doesn't exist for now
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missingPods.Insert(pod.Name)
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continue
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}
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readyPodCount++
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}
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if len(metrics) == 0 {
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return 0, 0, 0, time.Time{}, fmt.Errorf("did not receive metrics for any ready pods")
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}
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usageRatio, utilization, rawUtilization, err := metricsclient.GetResourceUtilizationRatio(metrics, requests, targetUtilization)
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if err != nil {
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return 0, 0, 0, time.Time{}, err
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}
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rebalanceUnready := len(unreadyPods) > 0 && usageRatio > 1.0
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if !rebalanceUnready && len(missingPods) == 0 {
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if math.Abs(1.0-usageRatio) <= c.tolerance {
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// return the current replicas if the change would be too small
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return currentReplicas, utilization, rawUtilization, timestamp, nil
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}
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// if we don't have any unready or missing pods, we can calculate the new replica count now
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return int32(math.Ceil(usageRatio * float64(readyPodCount))), utilization, rawUtilization, timestamp, nil
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}
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if len(missingPods) > 0 {
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if usageRatio < 1.0 {
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// on a scale-down, treat missing pods as using 100% of the resource request
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for podName := range missingPods {
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metrics[podName] = requests[podName]
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}
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} else if usageRatio > 1.0 {
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// on a scale-up, treat missing pods as using 0% of the resource request
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for podName := range missingPods {
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metrics[podName] = 0
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}
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}
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}
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if rebalanceUnready {
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// on a scale-up, treat unready pods as using 0% of the resource request
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for podName := range unreadyPods {
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metrics[podName] = 0
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}
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}
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// re-run the utilization calculation with our new numbers
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newUsageRatio, _, _, err := metricsclient.GetResourceUtilizationRatio(metrics, requests, targetUtilization)
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if err != nil {
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return 0, utilization, rawUtilization, time.Time{}, err
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}
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if math.Abs(1.0-newUsageRatio) <= c.tolerance || (usageRatio < 1.0 && newUsageRatio > 1.0) || (usageRatio > 1.0 && newUsageRatio < 1.0) {
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// return the current replicas if the change would be too small,
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// or if the new usage ratio would cause a change in scale direction
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return currentReplicas, utilization, rawUtilization, timestamp, nil
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}
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// return the result, where the number of replicas considered is
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// however many replicas factored into our calculation
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return int32(math.Ceil(newUsageRatio * float64(len(metrics)))), utilization, rawUtilization, timestamp, nil
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}
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// GetRawResourceReplicas calculates the desired replica count based on a target resource utilization (as a raw milli-value)
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// for pods matching the given selector in the given namespace, and the current replica count
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func (c *ReplicaCalculator) GetRawResourceReplicas(currentReplicas int32, targetUtilization int64, resource v1.ResourceName, namespace string, selector labels.Selector) (replicaCount int32, utilization int64, timestamp time.Time, err error) {
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metrics, timestamp, err := c.metricsClient.GetResourceMetric(resource, namespace, selector)
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if err != nil {
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return 0, 0, time.Time{}, fmt.Errorf("unable to get metrics for resource %s: %v", resource, err)
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}
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replicaCount, utilization, err = c.calcPlainMetricReplicas(metrics, currentReplicas, targetUtilization, namespace, selector)
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return replicaCount, utilization, timestamp, err
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}
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// GetMetricReplicas calculates the desired replica count based on a target metric utilization
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// (as a milli-value) for pods matching the given selector in the given namespace, and the
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// current replica count
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func (c *ReplicaCalculator) GetMetricReplicas(currentReplicas int32, targetUtilization int64, metricName string, namespace string, selector labels.Selector) (replicaCount int32, utilization int64, timestamp time.Time, err error) {
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metrics, timestamp, err := c.metricsClient.GetRawMetric(metricName, namespace, selector)
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if err != nil {
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return 0, 0, time.Time{}, fmt.Errorf("unable to get metric %s: %v", metricName, err)
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}
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replicaCount, utilization, err = c.calcPlainMetricReplicas(metrics, currentReplicas, targetUtilization, namespace, selector)
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return replicaCount, utilization, timestamp, err
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}
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// calcPlainMetricReplicas calculates the desired replicas for plain (i.e. non-utilization percentage) metrics.
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func (c *ReplicaCalculator) calcPlainMetricReplicas(metrics metricsclient.PodMetricsInfo, currentReplicas int32, targetUtilization int64, namespace string, selector labels.Selector) (replicaCount int32, utilization int64, err error) {
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podList, err := c.podsGetter.Pods(namespace).List(metav1.ListOptions{LabelSelector: selector.String()})
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if err != nil {
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return 0, 0, fmt.Errorf("unable to get pods while calculating replica count: %v", err)
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}
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if len(podList.Items) == 0 {
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return 0, 0, fmt.Errorf("no pods returned by selector while calculating replica count")
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}
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readyPodCount := 0
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unreadyPods := sets.NewString()
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missingPods := sets.NewString()
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for _, pod := range podList.Items {
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if pod.Status.Phase != v1.PodRunning || !hasPodBeenReadyBefore(&pod) {
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// save this pod name for later, but pretend it doesn't exist for now
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unreadyPods.Insert(pod.Name)
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delete(metrics, pod.Name)
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continue
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}
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if _, found := metrics[pod.Name]; !found {
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// save this pod name for later, but pretend it doesn't exist for now
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missingPods.Insert(pod.Name)
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continue
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}
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readyPodCount++
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}
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if len(metrics) == 0 {
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return 0, 0, fmt.Errorf("did not receive metrics for any ready pods")
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}
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usageRatio, utilization := metricsclient.GetMetricUtilizationRatio(metrics, targetUtilization)
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rebalanceUnready := len(unreadyPods) > 0 && usageRatio > 1.0
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if !rebalanceUnready && len(missingPods) == 0 {
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if math.Abs(1.0-usageRatio) <= c.tolerance {
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// return the current replicas if the change would be too small
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return currentReplicas, utilization, nil
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}
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// if we don't have any unready or missing pods, we can calculate the new replica count now
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return int32(math.Ceil(usageRatio * float64(readyPodCount))), utilization, nil
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}
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if len(missingPods) > 0 {
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if usageRatio < 1.0 {
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// on a scale-down, treat missing pods as using 100% of the resource request
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for podName := range missingPods {
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metrics[podName] = targetUtilization
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}
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} else {
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// on a scale-up, treat missing pods as using 0% of the resource request
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for podName := range missingPods {
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metrics[podName] = 0
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}
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}
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}
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if rebalanceUnready {
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// on a scale-up, treat unready pods as using 0% of the resource request
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for podName := range unreadyPods {
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metrics[podName] = 0
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}
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}
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// re-run the utilization calculation with our new numbers
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newUsageRatio, _ := metricsclient.GetMetricUtilizationRatio(metrics, targetUtilization)
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if math.Abs(1.0-newUsageRatio) <= c.tolerance || (usageRatio < 1.0 && newUsageRatio > 1.0) || (usageRatio > 1.0 && newUsageRatio < 1.0) {
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// return the current replicas if the change would be too small,
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// or if the new usage ratio would cause a change in scale direction
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return currentReplicas, utilization, nil
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}
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// return the result, where the number of replicas considered is
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// however many replicas factored into our calculation
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return int32(math.Ceil(newUsageRatio * float64(len(metrics)))), utilization, nil
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}
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// GetObjectMetricReplicas calculates the desired replica count based on a target metric utilization (as a milli-value)
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// for the given object in the given namespace, and the current replica count.
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func (c *ReplicaCalculator) GetObjectMetricReplicas(currentReplicas int32, targetUtilization int64, metricName string, namespace string, objectRef *autoscaling.CrossVersionObjectReference, selector labels.Selector) (replicaCount int32, utilization int64, timestamp time.Time, err error) {
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utilization, timestamp, err = c.metricsClient.GetObjectMetric(metricName, namespace, objectRef)
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if err != nil {
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return 0, 0, time.Time{}, fmt.Errorf("unable to get metric %s: %v on %s %s/%s", metricName, objectRef.Kind, namespace, objectRef.Name, err)
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}
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usageRatio := float64(utilization) / float64(targetUtilization)
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if math.Abs(1.0-usageRatio) <= c.tolerance {
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// return the current replicas if the change would be too small
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return currentReplicas, utilization, timestamp, nil
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}
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readyPodCount, err := c.getReadyPodsCount(namespace, selector)
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if err != nil {
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return 0, 0, time.Time{}, fmt.Errorf("unable to calculate ready pods: %s", err)
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}
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replicaCount = int32(math.Ceil(usageRatio * float64(readyPodCount)))
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return replicaCount, utilization, timestamp, nil
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}
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// @TODO(mattjmcnaughton) Many different functions in this module use variations
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// of this function. Make this function generic, so we don't repeat the same
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// logic in multiple places.
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func (c *ReplicaCalculator) getReadyPodsCount(namespace string, selector labels.Selector) (int64, error) {
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podList, err := c.podsGetter.Pods(namespace).List(metav1.ListOptions{LabelSelector: selector.String()})
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if err != nil {
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return 0, fmt.Errorf("unable to get pods while calculating replica count: %v", err)
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}
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if len(podList.Items) == 0 {
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return 0, fmt.Errorf("no pods returned by selector while calculating replica count")
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}
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readyPodCount := 0
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for _, pod := range podList.Items {
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if pod.Status.Phase == v1.PodRunning && podutil.IsPodReady(&pod) {
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readyPodCount++
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}
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}
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return int64(readyPodCount), nil
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}
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// GetExternalMetricReplicas calculates the desired replica count based on a
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// target metric value (as a milli-value) for the external metric in the given
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// namespace, and the current replica count.
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func (c *ReplicaCalculator) GetExternalMetricReplicas(currentReplicas int32, targetUtilization int64, metricName, namespace string, metricSelector *metav1.LabelSelector, podSelector labels.Selector) (replicaCount int32, utilization int64, timestamp time.Time, err error) {
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metricLabelSelector, err := metav1.LabelSelectorAsSelector(metricSelector)
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if err != nil {
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return 0, 0, time.Time{}, err
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}
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metrics, timestamp, err := c.metricsClient.GetExternalMetric(metricName, namespace, metricLabelSelector)
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if err != nil {
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return 0, 0, time.Time{}, fmt.Errorf("unable to get external metric %s/%s/%+v: %s", namespace, metricName, metricSelector, err)
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}
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utilization = 0
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for _, val := range metrics {
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utilization = utilization + val
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}
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readyPodCount, err := c.getReadyPodsCount(namespace, podSelector)
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if err != nil {
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return 0, 0, time.Time{}, fmt.Errorf("unable to calculate ready pods: %s", err)
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}
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usageRatio := float64(utilization) / float64(targetUtilization)
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if math.Abs(1.0-usageRatio) <= c.tolerance {
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// return the current replicas if the change would be too small
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return currentReplicas, utilization, timestamp, nil
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}
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return int32(math.Ceil(usageRatio * float64(readyPodCount))), utilization, timestamp, nil
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}
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// GetExternalPerPodMetricReplicas calculates the desired replica count based on a
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// target metric value per pod (as a milli-value) for the external metric in the
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// given namespace, and the current replica count.
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func (c *ReplicaCalculator) GetExternalPerPodMetricReplicas(currentReplicas int32, targetUtilizationPerPod int64, metricName, namespace string, metricSelector *metav1.LabelSelector) (replicaCount int32, utilization int64, timestamp time.Time, err error) {
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metricLabelSelector, err := metav1.LabelSelectorAsSelector(metricSelector)
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if err != nil {
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return 0, 0, time.Time{}, err
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}
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metrics, timestamp, err := c.metricsClient.GetExternalMetric(metricName, namespace, metricLabelSelector)
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if err != nil {
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return 0, 0, time.Time{}, fmt.Errorf("unable to get external metric %s/%s/%+v: %s", namespace, metricName, metricSelector, err)
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}
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utilization = 0
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for _, val := range metrics {
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utilization = utilization + val
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}
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replicaCount = currentReplicas
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usageRatio := float64(utilization) / (float64(targetUtilizationPerPod) * float64(replicaCount))
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if math.Abs(1.0-usageRatio) > c.tolerance {
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// update number of replicas if the change is large enough
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replicaCount = int32(math.Ceil(float64(utilization) / float64(targetUtilizationPerPod)))
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}
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utilization = int64(math.Ceil(float64(utilization) / float64(currentReplicas)))
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return replicaCount, utilization, timestamp, nil
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}
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// hasPodBeenReadyBefore returns true if the pod is ready or if it's not ready
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func hasPodBeenReadyBefore(pod *v1.Pod) bool {
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_, readyCondition := podutil.GetPodCondition(&pod.Status, v1.PodReady)
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if readyCondition == nil {
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return false
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}
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if readyCondition.Status == v1.ConditionTrue {
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return true
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}
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lastReady := readyCondition.LastTransitionTime.Time
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if pod.Status.StartTime == nil {
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return false
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}
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started := pod.Status.StartTime.Time
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// If last status change was longer than maxDelayOfInitialReadinessStatus after the pod was
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// created assume it was ready in the past.
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return lastReady.After(started.Add(maxDelayOfInitialReadinessStatus))
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}
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