code: public int getConnectionPoolSize(URL url) {
          RequestBuilder req = new RequestBuilder();
          req.host = url.getHost();
          req.port = url.getPort() < 0 ? url.getDefaultPort() : url.getPort();
          return _getPoolSize(req);
      }
docs: Get the HTTP connection pool size.
  
  @param url The host URL.
  @return The HTTP connection pool size.