code: public synchronized void fatalError(TaskAttemptID taskId, String msg)
    throws IOException {
      LOG.fatal("Task: " + taskId + " - Killed : " + msg);
      TaskInProgress tip = runningTasks.get(taskId);
      if (tip != null) {
        tip.reportDiagnosticInfo("Error: " + msg);
        purgeTask(tip, true);
      }
    }
docs: A child task had a fatal error. Kill the task.