WatchUpdate() listen namespaces has limits

[oldthreefeng]

we have situations. we get 50+ namespaces in apollo

func main() {
	        conf := GetApollConf(apolloId,"default", namespaces)
	        apolloClient := apollo.NewClient(conf)
		go func() {
			for changeEvent := range apolloClient.WatchUpdate() {
				log.Info("apollo : ", log.Reflect("change",changeEvent))
			}
		}()
}
func GetApollConf(appid, cluster string, namespaces []string) *apollo.Conf {
	addr := os.Getenv(apollo.ADDR)
	if appid == "" || len(namespaces) == 0 || addr == "" {
		return nil
	}
	return apollo.NewConf(appid, cluster, addr, "", namespaces)
}

if len(namespaces) > 50+( not exact), we cant watch any update from apollo changes.
when namespaces less then 50(not exact), we can watch. can anyone helps me to slove?