public synchronized void connectWithRef(String url, final int connCount, Object ref) throws NotifyRemotingException {
        if (ENABLE_LOOPBACK_CONNECTION) {
            url = this.tryGetLoopbackURL(url);
        }
        final Set<Object> refs = this.getReferences(url);
        this.remotingClient.connect(url, connCount);
        refs.add(ref);
    }
Whether to enable loopback connection for metaq client, default is false.
metamorphosis-client/src/main/java/com/taobao/metamorphosis/client/RemotingClientWrapper.java