code: public static Set<String> killAllSpawnedHadoopJobs(String logFilePath, Logger log) {
      Set<String> allSpawnedJobs = findApplicationIdFromLog(logFilePath, log);
      log.info("applicationIds to kill: " + allSpawnedJobs);
  
      for (String appId : allSpawnedJobs) {
        try {
          killJobOnCluster(appId, log);
        } catch (Throwable t) {
          log.warn("something happened while trying to kill this job: " + appId, t);
        }
      }
  
      return allSpawnedJobs;
    }
docs: Pass in a log file, this method will find all the hadoop jobs it has launched, and kills it
  
  Only works with Hadoop2
  
  @return a Set<String>. The set will contain the applicationIds that this job tried to kill.