public static ShuffleHandler get() {
    Preconditions.checkState(started.get(),
        "ShuffleHandler must be started before invoking get");
    return INSTANCE;
  }
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