public void stop() throws IOException, InterruptedException {
    LOG.info("Stopping LlapOutputFormatService");

    if (listeningChannelFuture != null) {
      listeningChannelFuture.channel().close().sync();
      listeningChannelFuture = null;
    } else {
      LOG.warn("LlapOutputFormatService does not appear to have a listening port to close.");
    }

    eventLoopGroup.shutdownGracefully(1, WAIT_TIME, TimeUnit.SECONDS).sync();
  }
Responsible for sending back result set data to the connections
made by external clients via the LLAP input format.
ql/src/java/org/apache/hadoop/hive/llap/LlapOutputFormatService.java