code: public static void main(String[] args) {
      if (args.length != 0) {
        LOG.info("java -cp {} {}", RuntimeConstants.ALLUXIO_JAR,
            AlluxioJobWorker.class.getCanonicalName());
        System.exit(-1);
      }
  
      if (!ConfigurationUtils.masterHostConfigured(ServerConfiguration.global())) {
        System.out.println(ConfigurationUtils
            .getMasterHostNotConfiguredMessage("Alluxio job worker"));
        System.exit(1);
      }
  
      if (!ConfigurationUtils.jobMasterHostConfigured(ServerConfiguration.global())) {
        System.out.println(ConfigurationUtils
            .getJobMasterHostNotConfiguredMessage("Alluxio job worker"));
        System.exit(1);
      }
  
      CommonUtils.PROCESS_TYPE.set(CommonUtils.ProcessType.JOB_WORKER);
      MasterInquireClient masterInquireClient =
          MasterInquireClient.Factory.create(ServerConfiguration.global());
      try {
        RetryUtils.retry("load cluster default configuration with master", () -> {
          InetSocketAddress masterAddress = masterInquireClient.getPrimaryRpcAddress();
          ServerConfiguration.loadClusterDefaults(masterAddress);
        },
            RetryUtils.defaultWorkerMasterClientRetry(
                ServerConfiguration.getDuration(PropertyKey.WORKER_MASTER_CONNECT_RETRY_TIMEOUT)));
      } catch (IOException e) {
        ProcessUtils.fatalError(LOG,
            "Failed to load cluster default configuration for job worker: %s", e.getMessage());
      }
      JobWorkerProcess process = JobWorkerProcess.Factory.create();
      ProcessUtils.run(process);
    }
docs: Starts the Alluxio job worker.
  
  @param args command line arguments, should be empty