code: def _mapreduce_task_metrics(self, running_jobs, auth, ssl_verify, addl_tags):
          
          for job_stats in itervalues(running_jobs):
  
              metrics_json = self._rest_request_to_json(
                  job_stats['tracking_url'], auth, ssl_verify, 'tasks', self.MAPREDUCE_SERVICE_CHECK, tags=addl_tags
              )
  
              if metrics_json.get('tasks'):
                  if metrics_json['tasks'].get('task'):
  
                      for task in metrics_json['tasks']['task']:
                          task_type = task.get('type')
  
                          if task_type:
                              tags = [
                                  'app_name:' + job_stats['app_name'],
                                  'user_name:' + job_stats['user_name'],
                                  'job_name:' + job_stats['job_name'],
                                  'task_type:' + str(task_type).lower(),
                              ]
  
                              tags.extend(addl_tags)
  
                              if task_type == 'MAP':
                                  self._set_metrics_from_json(task, self.MAPREDUCE_MAP_TASK_METRICS, tags)
  
                              elif task_type == 'REDUCE':
                                  self._set_metrics_from_json(task, self.MAPREDUCE_REDUCE_TASK_METRICS, tags)
docs: Get metrics for each MapReduce task
          Return a dictionary of {task_id: 'tracking_url'} for each MapReduce task