https://github.com/kubernetes/kubernetes/blob/87f9429087d4e31201412548517d36e83abebc8d/pkg/controller/cronjob/cronjob_controller.go#L220-L228

cronjob_controller.go

// from: https://github.com/kubernetes/kubernetes/blob/87f9429087d4e31201412548517d36e83abebc8d/pkg/controller/cronjob/cronjob_controller.go#L220-L228

// Remove any job reference from the active list if the corresponding job does not exist any more.
// Otherwise, the cronjob may be stuck in active mode forever even though there is no matching
// job running.
for _, j := range sj.Status.Active {
	if found := childrenJobs[j.UID]; !found {
		recorder.Eventf(sj, v1.EventTypeNormal, "MissingJob", "Active job went missing: %v", j.Name)
		deleteFromActiveList(sj, j.UID)
	}
}