code: public static RserverConf newLocalInstance(Properties p) {
          RserverConf server = null;
          if (RserveDaemon.isWindows() || !UNIX_OPTIMIZE) {
              while (!isPortAvailable(RserverPort)) {
                  RserverPort++;
              }
              server = new RserverConf(null, RserverPort, null, null, p);
          } else { // Unix supports multi-sessions natively, so no need to open a different Rserve on a new port
              server = new RserverConf(null, -1, null, null, p);
          }
          return server;
      }
docs: if we want to re-use older sessions. May wrongly fil if older session is already stucked...