code: public static void main(String[] args) {
      if (args.length != 0) {
        LOG.info("java -cp {} {}", RuntimeConstants.ALLUXIO_JAR,
            AlluxioMaster.class.getCanonicalName());
        System.exit(-1);
      }
  
      CommonUtils.PROCESS_TYPE.set(CommonUtils.ProcessType.MASTER);
      MasterProcess process;
      try {
        process = AlluxioMasterProcess.Factory.create();
      } catch (Throwable t) {
        ProcessUtils.fatalError(LOG, t, "Failed to create master process");
        // fatalError will exit, so we shouldn't reach here.
        throw t;
      }
  
      // Register a shutdown hook for master, so that master closes the journal files when it
      // receives SIGTERM.
      ProcessUtils.stopProcessOnShutdown(process);
      ProcessUtils.run(process);
    }
docs: Starts the Alluxio master.
  
  @param args command line arguments, should be empty