code: protected void sleep(long ms) throws IOException {
      try {
        Thread.sleep(ms);
      } catch (InterruptedException e) {
        LOG.error("Interrupted when sleeping", e);
        Thread.currentThread().interrupt();
        throw new IOException("Received interruption");
      }
    }
docs: Sleep for n milliseconds.
  Throw IOException when interrupted.
  @param ms
  @throws IOException