Cluster Autoscaler monitors Pods through a watch on Kube API. It checks every 10 seconds whether there are any unschedulable Pods (configurable through the --scan-interval flag). In that context, a Pod is unschedulable when the Kubernetes Scheduler is unable to find a node that can accommodate it. For example, a Pod can request more memory than what is available on any of the worker nodes.
Cluster Autoscaler assumes that requested nodes will appear within 15 minutes (configurable through the --max-node-provision-time flag). If that period expires and a new...