Laravel5.6 MongoDB 事务问题

 $session = DB::getMongoClient()->startSession();        
 $session = DB::connection('mongodb')->getMongoClient()->startSession();
 $session->startTransaction();
 try {           
            $objectFK  = new ObjectFK();
            $objectFK->fk_name = '测试事务';
            $objectFK->save();
            $ObjectFieldsK  = new ObjectFields();
            $ObjectFieldsK->alias = '测试事务';
            $ObjectFieldsK->save();
            // $session->commitTransaction();
  } catch (Exception $e) {
                $session->abortTransaction();
  }
该行注释后数据依然进入集合
  // $session->commitTransaction();Copy