public function disconnectFromNSQD($host, $port)
    {
        $key = "$host:$port";
        if (!isset($this->nsqdTCPAddrsConnNum[$key])) {
            throw new NsqException("not connected");
        }

        foreach ($this->getConnections() as $conn) {
            if ($conn->getHost() === $host && $conn->getPort() === $port) {
                $conn->tryClose();
            }
        }
        $this->nsqdTCPAddrsConnNum[$key] = 0;
    }