scrape/manager.go
func (m *Manager) setJitterSeed(labels labels.Labels) error {
	h := fnv.New64a()
	hostname, err := getFqdn()
	if err != nil {
		return err
	}
	if _, err := fmt.Fprintf(h, "%s%s", hostname, labels.String()); err != nil {
		return err
	}
	m.jitterSeed = h.Sum64()
	return nil
}
func (m *Manager) setJitterSeed(labels labels.Labels) error {
	h := fnv.New64a()
	hostname, err := getFqdn()
	if err != nil {
		return err
	}
	if _, err := fmt.Fprintf(h, "%s%s", hostname, labels.String()); err != nil {
		return err
	}
	m.jitterSeed = h.Sum64()
	return nil
}
// setJitterSeed calculates a global jitterSeed per server relying on extra label set.