Spring transactions behaviour

Question

It seems that when a transactional spring method with propagation of NESTED calls another transactional method with propagation REQUIRED, the inner transaction can force the rollback of the outer logical transaction. Anyone can confirm?

I would like to handle RuntimeException and not rollback the outer transaction, example:

@Transactional
class A {

    @Autowired
    B b;

    @Autowired
    C c;

    void methodA() { // outer transaction, this should not be rollback but currently getting UnexpectedRollbackException
        b.methodB(() -> c.methodC());
    }
}

@Transactional(propagation = Propagation.NESTED)
class B {

    void methodB(Runnable action) { // inner nested transaction
        try{
            action.run();
        } catch (Exception e){
           // nothing
        }
    }
}

@Transactional
class C {
    void methodC() { // inner required transaction
        throw new RuntimeException();
    }
}

user991710 user991710 · Accepted Answer · 2018-05-15T13:48:00

Why wouldn't it? Propagation NESTED begins a transaction within the current one if one exists, and behaves like REQUIRED otherwise. The javadocs state:

/**
 * Support a current transaction; create a new one if none exists.
 * Analogous to the EJB transaction attribute of the same name.
 * <p>This is typically the default setting of a transaction definition,
 * and typically defines a transaction synchronization scope.
 */
int PROPAGATION_REQUIRED = 0;

/**
 * Execute within a nested transaction if a current transaction exists,
 * behave like {@link #PROPAGATION_REQUIRED} else. There is no analogous
 * feature in EJB.
 * <p><b>NOTE:</b> Actual creation of a nested transaction will only work on
 * specific transaction managers. Out of the box, this only applies to the JDBC
 * {@link org.springframework.jdbc.datasource.DataSourceTransactionManager}
 * when working on a JDBC 3.0 driver. Some JTA providers might support
 * nested transactions as well.
 * @see org.springframework.jdbc.datasource.DataSourceTransactionManager
 */
int PROPAGATION_NESTED = 6;

Of note is that NESTED is truly only supported if your JDBC driver supports savepoints. This means:

No existing transaction
A (NESTED)
B (REQUIRED)

Would have the following behaviour:

begin; -- called prior to A but in A's 
A.doSomething();
B.doSomethingThatCausesException()
rollback;

And

Existing transaction
A (NESTED)
B (REQUIRED)

Would have the following behaviour:

begin; -- called outside of the scope of A
savepoint A_savepoint
A.doSomething();
B.doSomethingThatCausesException();
rollback A_savepoint;

if your JDBC driver supports nested transactions. Otherwise, it would behave like the first scenario. See also this answer.

That said, I believe that savepoints are more trouble than they're worth and you will save yourself a lot of potential trouble if you're treating any of your database operations atomically.

Spring transactions behaviour

1 Answers