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HPA: only send updates when the status has changed

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This commit only sends updates if the status has actually changed.
Since the HPA runs at a regular interval, this should reduce the volume
of writes, especially on short HPA intervals with relatively constant
metrics.
This commit is contained in:
Solly Ross
2017-06-06 15:57:05 -04:00
parent 4a01f44b73
commit 00a19f1289
3 changed files with 115 additions and 14 deletions
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48
pkg/controller/podautoscaler/horizontal.go
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@@ -22,6 +22,7 @@ import (
"time"
"github.com/golang/glog"
apiequality "k8s.io/apimachinery/pkg/api/equality"
"k8s.io/apimachinery/pkg/api/errors"
"k8s.io/apimachinery/pkg/api/resource"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -371,6 +372,12 @@ func (a *HorizontalController) reconcileAutoscaler(hpav1Shared *autoscalingv1.Ho
return fmt.Errorf("failed to convert the given HPA to %s: %v", autoscalingv2.SchemeGroupVersion.String(), err)
}
hpa := hpaRaw.(*autoscalingv2.HorizontalPodAutoscaler)
hpaStatusOriginalRaw, err := api.Scheme.DeepCopy(&hpa.Status)
if err != nil {
a.eventRecorder.Event(hpav1Shared, v1.EventTypeWarning, "FailedConvertHPA", err.Error())
return fmt.Errorf("failed to deep-copy the HPA status: %v", err)
}
hpaStatusOriginal := hpaStatusOriginalRaw.(*autoscalingv2.HorizontalPodAutoscalerStatus)
reference := fmt.Sprintf("%s/%s/%s", hpa.Spec.ScaleTargetRef.Kind, hpa.Namespace, hpa.Spec.ScaleTargetRef.Name)
@@ -378,7 +385,7 @@ func (a *HorizontalController) reconcileAutoscaler(hpav1Shared *autoscalingv1.Ho
if err != nil {
a.eventRecorder.Event(hpa, v1.EventTypeWarning, "FailedGetScale", err.Error())
setCondition(hpa, autoscalingv2.AbleToScale, v1.ConditionFalse, "FailedGetScale", "the HPA controller was unable to get the target's current scale: %v", err)
a.update(hpa)
a.updateStatusIfNeeded(hpaStatusOriginal, hpa)
return fmt.Errorf("failed to query scale subresource for %s: %v", reference, err)
}
setCondition(hpa, autoscalingv2.AbleToScale, v1.ConditionTrue, "SucceededGetScale", "the HPA controller was able to get the target's current scale")
@@ -412,7 +419,10 @@ func (a *HorizontalController) reconcileAutoscaler(hpav1Shared *autoscalingv1.Ho
} else {
metricDesiredReplicas, metricName, metricStatuses, metricTimestamp, err = a.computeReplicasForMetrics(hpa, scale, hpa.Spec.Metrics)
if err != nil {
a.updateCurrentReplicasInStatus(hpa, currentReplicas)
a.setCurrentReplicasInStatus(hpa, currentReplicas)
if err := a.updateStatusIfNeeded(hpaStatusOriginal, hpa); err != nil {
utilruntime.HandleError(err)
}
a.eventRecorder.Event(hpa, v1.EventTypeWarning, "FailedComputeMetricsReplicas", err.Error())
return fmt.Errorf("failed to compute desired number of replicas based on listed metrics for %s: %v", reference, err)
}
@@ -489,7 +499,10 @@ func (a *HorizontalController) reconcileAutoscaler(hpav1Shared *autoscalingv1.Ho
if err != nil {
a.eventRecorder.Eventf(hpa, v1.EventTypeWarning, "FailedRescale", "New size: %d; reason: %s; error: %v", desiredReplicas, rescaleReason, err.Error())
setCondition(hpa, autoscalingv2.AbleToScale, v1.ConditionFalse, "FailedUpdateScale", "the HPA controller was unable to update the target scale: %v", err)
a.updateCurrentReplicasInStatus(hpa, currentReplicas)
a.setCurrentReplicasInStatus(hpa, currentReplicas)
if err := a.updateStatusIfNeeded(hpaStatusOriginal, hpa); err != nil {
utilruntime.HandleError(err)
}
return fmt.Errorf("failed to rescale %s: %v", reference, err)
}
setCondition(hpa, autoscalingv2.AbleToScale, v1.ConditionTrue, "SucceededRescale", "the HPA controller was able to update the target scale to %d", desiredReplicas)
@@ -501,7 +514,8 @@ func (a *HorizontalController) reconcileAutoscaler(hpav1Shared *autoscalingv1.Ho
desiredReplicas = currentReplicas
}
return a.updateStatusWithReplicas(hpa, currentReplicas, desiredReplicas, metricStatuses, rescale)
a.setStatus(hpa, currentReplicas, desiredReplicas, metricStatuses, rescale)
return a.updateStatusIfNeeded(hpaStatusOriginal, hpa)
}
func (a *HorizontalController) shouldScale(hpa *autoscalingv2.HorizontalPodAutoscaler, currentReplicas, desiredReplicas int32, timestamp time.Time) bool {
@@ -528,14 +542,14 @@ func (a *HorizontalController) shouldScale(hpa *autoscalingv2.HorizontalPodAutos
return false
}
func (a *HorizontalController) updateCurrentReplicasInStatus(hpa *autoscalingv2.HorizontalPodAutoscaler, currentReplicas int32) {
err := a.updateStatusWithReplicas(hpa, currentReplicas, hpa.Status.DesiredReplicas, hpa.Status.CurrentMetrics, false)
if err != nil {
utilruntime.HandleError(err)
}
// setCurrentReplicasInStatus sets the current replica count in the status of the HPA.
func (a *HorizontalController) setCurrentReplicasInStatus(hpa *autoscalingv2.HorizontalPodAutoscaler, currentReplicas int32) {
a.setStatus(hpa, currentReplicas, hpa.Status.DesiredReplicas, hpa.Status.CurrentMetrics, false)
}
func (a *HorizontalController) updateStatusWithReplicas(hpa *autoscalingv2.HorizontalPodAutoscaler, currentReplicas, desiredReplicas int32, metricStatuses []autoscalingv2.MetricStatus, rescale bool) error {
// setStatus recreates the status of the given HPA, updating the current and
// desired replicas, as well as the metric statuses
func (a *HorizontalController) setStatus(hpa *autoscalingv2.HorizontalPodAutoscaler, currentReplicas, desiredReplicas int32, metricStatuses []autoscalingv2.MetricStatus, rescale bool) {
hpa.Status = autoscalingv2.HorizontalPodAutoscalerStatus{
CurrentReplicas: currentReplicas,
DesiredReplicas: desiredReplicas,
@@ -548,11 +562,19 @@ func (a *HorizontalController) updateStatusWithReplicas(hpa *autoscalingv2.Horiz
now := metav1.NewTime(time.Now())
hpa.Status.LastScaleTime = &now
}
return a.update(hpa)
}
func (a *HorizontalController) update(hpa *autoscalingv2.HorizontalPodAutoscaler) error {
// updateStatusIfNeeded calls updateStatus only if the status of the new HPA is not the same as the old status
func (a *HorizontalController) updateStatusIfNeeded(oldStatus *autoscalingv2.HorizontalPodAutoscalerStatus, newHPA *autoscalingv2.HorizontalPodAutoscaler) error {
// skip a write if we wouldn't need to update
if apiequality.Semantic.DeepEqual(oldStatus, &newHPA.Status) {
return nil
}
return a.updateStatus(newHPA)
}
// updateStatus actually does the update request for the status of the given HPA
func (a *HorizontalController) updateStatus(hpa *autoscalingv2.HorizontalPodAutoscaler) error {
// convert back to autoscalingv1
hpaRaw, err := UnsafeConvertToVersionVia(hpa, autoscalingv1.SchemeGroupVersion)
if err != nil {