GetResourceReplicas

metrics, timestamp, err := c.metricsClient.GetResourceMetric(resource, namespace, selector, container)
 获取指标以及时间

podList, err := c.podLister.Pods(namespace).List(selector)
 获取工作负载所有关联pod

readyPodCount, unreadyPods, missingPods, ignoredPods := groupPods(podList, metrics, resource, c.cpuInitializationPeriod, c.delayOfInitialReadinessStatus)
 removeMetricsForPods(metrics, ignoredPods)
 removeMetricsForPods(metrics, unreadyPods)
 对pod进行分组，readyPodCount, unreadyPods, missingPods, ignoredPods并从指标中去除ignoredPods，unreadyPods

requests, err := calculatePodRequests(podList, container, resource)
 计算所有pod的request用量

usageRatio, utilization, rawUtilization, err := metricsclient.GetResourceUtilizationRatio(metrics, requests, targetUtilization)
获取使用比率，当前资源利用率，平均使用量（基于request计算）

rebalanceIgnored := len(unreadyPods) > 0 && usageRatio > 1.0 未就绪pod大于0，并且usageRatio>1.0。可以忽略伸缩。等待就绪pod完成，会重新计算指标，避免频繁扩容

 if !rebalanceIgnored && len(missingPods) == 0 {
  if math.Abs(1.0-usageRatio) <= c.tolerance {
   // return the current replicas if the change would be too small
   return currentReplicas, utilization, rawUtilization, timestamp, nil
  }

  // if we don't have any unready or missing pods, we can calculate the new replica count now
  return int32(math.Ceil(usageRatio * float64(readyPodCount))), utilization, rawUtilization, timestamp, nil
 }

...