public static void initializeAndStart(Configuration conf) throws Exception {
    if (!initing.getAndSet(true)) {
      INSTANCE = new ShuffleHandler(conf);
      INSTANCE.start();
      started.set(true);
    }
  }
Should the shuffle use posix_fadvise calls to manage the OS cache during
sendfile
llap-server/src/java/org/apache/hadoop/hive/llap/shufflehandler/ShuffleHandler.java