private SanityChecker sanityCheckQueue(SanityChecker sc) {
    if (sc == null) {
      sc = new SanityChecker(waitQueue);
    }
    sc.run();
    return sc;
  }
Assumes the epic lock is already taken.
llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/TaskExecutorService.java