code: private void checkOwnMaster() throws Exception {
          int retry_times = 10;
  
          StormClusterState zkClient = data.getStormClusterState();
          for (int i = 0; i < retry_times; i++, JStormUtils.sleepMs(sleepTime)) {
  
              if (!zkClient.leader_existed()) {
                  continue;
              }
  
              String zkHost = zkClient.get_leader_host();
              if (hostPort.equals(zkHost)) {
                  // current process own master
                  return;
              }
              LOG.warn("Current nimbus has started thrift, but fail to set as leader in zk:" + zkHost);
          }
  
          String err = "Current nimbus failed to set as leader in zk, halting process";
          LOG.error(err);
          JStormUtils.halt_process(0, err);
  
      }
docs: Check whether current node is master