code: public synchronized void asyncSetPersistentTimestamp(final long newPersistentTimestamp) {
      new Thread() {
        @Override
        public void run() {
          try {
            chronosServerWatcher.setPersistentTimestamp(newPersistentTimestamp);
            isAsyncSetPersistentTimestamp = false;
          } catch (Exception e) {
            LOG.fatal("Error to set persistent timestamp, exit immediately");
            System.exit(0);
          }
        }
      }.start();
    }
docs: Create a new thread to asynchronously set persistent timestamp in ZooKeeper.
  
  @param newPersistentTimestamp the new timestamp to set