Async and transactional methods

Question

I have a web application that imports from a file to the database. The method is asynchronous and transactional, reads and inserts objects. The problem is that the import method takes 5 or 6 minutes. If I throw twice the import method without the transaction closes, the second method gets repeated ids for inserts. The first run just fine, but when you commit the secondary fails. This is my code:

@Controller
public class IndexController {

    @Autowired
    private fooServicio fService;

    @RequestMapping(value="/", method = RequestMethod.GET)
    public final ModelAndView printIndex(MultipartFile file) 
    {
        ModelAndView view = new ModelAndView("index");


        foService.import(file);

        view.addObject("message", "The file is loading"); 
        return view;        
    }
}

@Service
@Transactional(readOnly = true)
public class FooServiceImpl implements FooService {

    @Async
    @Override
    @Transactional(readOnly = false)
    public final void import(final MultipartFile file) throws ServiceException {
            //Read file and inserts
    }
} 

How can i fix this? Is there a way to manage asynchronous methods with a tail? For a method that does not start until another finishes.