void run() {
      queue.apply(this);
      if (firstProblematic != null) {
        final StringBuilder sb = new StringBuilder(
            "Found finishable task behind non-finishable in the queue: ");
        sb.append(firstProblematic).append(" was after ").append(firstCannotFinish).append("; ");
        queue.apply(new Function<TaskExecutorService.TaskWrapper, Boolean>() {
          @Override
          public Boolean apply(TaskWrapper input) {
            sb.append(input).append(", ");
            return true;
          }
        });
        LOG.error(sb.toString());
      }
      firstCannotFinish = firstProblematic = null;
    }
Assumes the epic lock is already taken.
llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/TaskExecutorService.java