hold read lock while reading brokers

client.go

@@ -161,6 +161,8 @@ func (client *client) Config() *Config {
 }
 
 func (client *client) Brokers() []*Broker {
+	client.lock.RLock()
+	defer client.lock.RUnlock()
 	brokers := make([]*Broker, 0)
 	for _, broker := range client.brokers {
 		brokers = append(brokers, broker)