事务隔离级别如何使用多个@Transactional 改变整个事务

Question

@Transactional
public void a() {
  b();
  c();
}

@Transactonal(isolation = Isolation.SERIALIZABLE)
public void b() {
  // some code with update in db
}

public void c() {
  // some code with selects and updates in db
}

What isolation level will be used in method 'c'? As far as I understand, it all will be a one transaction. And in method 'b' we just join to current transaction and change its isolation level. But will it be changed back to default after method b execution?

I ask it because in such situation on big load we got 'PSQLException: ERROR: could not serialize access due to concurrent update' in method 'c', although i want to have a default isolation level in method 'c'.

Answer 1

@Transactional
public void a() {
  b();
  c();
}

@Transactonal(isolation = Isolation.SERIALIZABLE)
public void b() {
  // some code with update in db
}

public void c() {
  // some code with selects and updates in db
}

Calling another method from the same class with @Transactional will have no effect since proxies can not work on invokation from the same class. It is how proxies behind the scenes, work that does not allow such a thing.

However if you call another method from another spring bean, that has @Transactional this will be respected.

@Service
public SpringClass {

    @Transactional
    public void a() {
      anotherSpringClass.b();
      anotherSpringClass.c();
    }

}

There you can define that you want a nested transaction to be opened with another isolation level.

@Service
public class AnotherSpringClass {

@Transactional(propagation = Propagation.NESTED, isolation = Isolation.SERIALIZABLE)
public void b() {
  // some code with update in db
}

}