code: public void run() {
      while (running) {
        try {
          cleanUpInitializedJobsList();
          selectJobsToInitialize();
          if (!this.isInterrupted()) {
            Thread.sleep(sleepInterval);
          }
        } catch (InterruptedException e) {
          LOG.error("Job Initialization poller interrupted"
              + StringUtils.stringifyException(e));
        }
      }
    }
docs: This is main thread of initialization poller, We essentially do
  following in the main threads:
  
  <ol>
  <li> Clean up the list of initialized jobs list which poller maintains
  </li>
  <li> Select jobs to initialize in the polling interval.</li>
  </ol>