code: public synchronized void shuffleError(TaskAttemptID taskId, String message)
    throws IOException {
      LOG.fatal("Task: " + taskId + " - Killed due to Shuffle Failure: " + message);
      TaskInProgress tip = runningTasks.get(taskId);
      if (tip != null) {
        tip.reportDiagnosticInfo("Shuffle Error: " + message);
        purgeTask(tip, true);
      }
    }
docs: A reduce-task failed to shuffle the map-outputs. Kill the task.