Spring Async用于批量插入

Question

I'm using spring boot. I was new to spring and started a spring project. So I didn't know about pre defined repositories (JPA, CRUD) which can be easily implemented. In case, I wanted to save a bulk data, so I use for loop and save one by one, Its taking more time. So I tried to use @Async . But it doesn't also work, is my concept wrong?

@Async has two limitation

• it must be applied to public methods only
• self-invocation – calling the async method from within the same class won't work

1) Controller

for(i=0;i < array.length();i++){
    // Other codes
    gaugeCategoryService.saveOrUpdate(getEditCategory);
}

2) Dao implementation

@Repository
public class GaugeCategoryDaoImpl implements GaugeCategoryDao {
    // Other codings

    @Async
    @Override   
    public void saveOrUpdate(GaugeCategory GaugeCategory) {
        sessionFactory.getCurrentSession().saveOrUpdate(GaugeCategory);
    }
}

After removing @Async , it working normally. But with that annotation it doesn't work. Is there any alternative method for time consuming? Thanks in advance.

Answer 1

the @Async annotation creates a thread for every time you call that method. but you need to enable it in your class using this annotation @EnableAsync You also need to configure the asyncExecutor Bean. You can find more details here : https://spring.io/guides/gs/async-method/

Answer 2

In my opinion, there are several issues with your code:

1. You overwrite the saveOrUpdate() method without any need to do so. A simple call to "super()" should have been enough to make @Async work.

2. I guess that you somewhere (within your controller class?) declare a transactional context. That one usually applies to the current thread. By using @Async, you might leave this transaction context as (because of the async DAO execution), the main thread may already be finished when saveOrUpdate() is called. And even though I currently don't know it exactly, there is a good change that the declared transaction is only valid for the current thread.

One possble fix: create an additional component like AsyncGaugeCategoryService or so like this:

@Component
public class AsyncGaugeCategoryService {

    private final GaugeCategoryDao gaugeCategoryDao;

    @Autowired
    public AsyncGaugeCategoryService(GaugeCategoryDao gaugeCategoryDao) {
        this.gaugeCategoryDao = gaugeCategoryDao;
    }

    @Async
    @Transactional
    public void saveOrUpdate(GaugeCategory gaugeCategory) {
        gaugeCategoryDao.saveOrUpdate(gaugeCategory);
    }
}

Then inject the service instead of the DAO into your controller class. This way, you don't need to overwrite any methods, and you should have a valid transactional context within your async thread.

But be warned that your execution flow won't give you any hint if something goes wrong while storing into the database. You'll have to check the log files to detect any problems.