@Override
  public QueryIdentifier findQueryByFragment(String fragmentId) {
    synchronized (lock) {
      TaskWrapper taskWrapper = knownTasks.get(fragmentId);
      return taskWrapper == null ? null : taskWrapper.getTaskRunnerCallable()
          .getFragmentInfo().getQueryInfo().getQueryIdentifier();
    }
  }
Worker that takes tasks from wait queue and schedule it for execution.
llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/TaskExecutorService.java