subchannel.go
func (subChMap *subChannelMap) get(serviceName string) (*SubChannel, bool) {
	subChMap.RLock()
	sc, ok := subChMap.subchannels[serviceName]
	subChMap.RUnlock()
	return sc, ok
}
func (subChMap *subChannelMap) get(serviceName string) (*SubChannel, bool) {
	subChMap.RLock()
	sc, ok := subChMap.subchannels[serviceName]
	subChMap.RUnlock()
	return sc, ok
}
// Get subchannel if, we have one