Spring Rabbit和JDBC事务问题

Question

I have two spring rabbit consumers A and B.

consumer A:

protected void process(Message amqpMessage, Channel channel)
            throws Exception {
   Session mysession=sessionRepository.findOne(5);
   mysession.setMyField("bla");
   sessionRepository.save(mysession);
   ServicesHelper.convertAndSend(<Consumer B token>, mysession.getId());

}

Consumer B:

protected void process(Message amqpMessage, Channel channel)
            throws Exception {
   //getting event from message
   Long sessionId=5;
   Session mysession=sessionRepository.findOne(sessionId);
   mysession.setMyField("bla-bla");
   //And I get there unpredictable optimistic locking exception. 
   sessionRepository.save(mysession);


}

It seems like jdbc transaction in consumer A is being committed after exit from listener method, that's why overlapping is possible. My 'session' entiry has a @Version column, that;s why I discovered this issue. How to avoid it and is it good approach to do this? I just need to process a session in consumer A and then pass to consumer B.

Answer 1

I think you may be talking about spring-data here not spring-jdbc . If this is the case ( apologies if it's not ) and you are using CrudRepository then it's probably because interactions with the repository are all @Transactional .

For example, here is the actual signature of save

@Transactional
    public <S extends T> S save(S entity) {

        if (entityInformation.isNew(entity)) {
            em.persist(entity);
            return entity;
        } else {
            return em.merge(entity);
        }
    }

I would suggest refactoring to the following and trying again :-

protected void process(Message amqpMessage, Channel channel)
            throws Exception {

   ServicesHelper.convertAndSend(<Consumer B token>,adaptSession().getId()));

}

@Transactional
protected Session adaptSession(){
   Session mysession=sessionRepository.findOne(5);
   mysession.setMyField("bla");
   sessionRepository.save(mysession);
   return mysession; 
}

and

@Transactional
protected void process(Message amqpMessage, Channel channel)
            throws Exception {
   //getting event from message
   Long sessionId=5;
   Session mysession=sessionRepository.findOne(sessionId);
   mysession.setMyField("bla-bla");
   //And I get there unpredictable optimistic locking exception. 
   sessionRepository.save(mysession);
}

Which should make the transactional units match up. Try that and me know.