Spring @Transactional Annotation : Self Invocation

If you call saveAB and saveB throws an Exception, your transaction will roll back.

Self-invocation doesn't break the transactional context because the default transaction propagation is REQUIRED, meaning that the same transaction context is reused when calling a new @Transactional method on a new bean.

However, inside the same bean, calling new methods doesn't go through the TransactionalInterceptor, hence the very same transaction context is reused.

What I don't understand is why do people say self invocation breaks transaction?

I never heard that self-invocation breaks transaction. All I know is that self-invocation will not start a new transaction and you already mentioned the reason why.

Snippet from Spring's Transaction Management Specification

Note In proxy mode (which is the default), only external method calls coming in through the proxy are intercepted. This means that self-invocation, in effect, a method within the target object calling another method of the target object, will not lead to an actual transaction at runtime even if the invoked method is marked with @Transactional.

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If you remove @Transaction annotation from saveAB(), you would observe that method saveA() and saveB() would not run under transaction even though it is annotated with @Transactional. However, if you call saveA() or saveB() from outside the class, it will run under transaction as expected. That is the reason why people advice to be cautious with self-invocation.

public void saveAB(A a, B b)
{
    saveA(a);
    saveB(b);
}

@Transactional
public void saveA(A a)
{
    dao.saveA(a);
}

@Transactional
public void saveB(B b)
{
    dao.saveB(b);
}

In my view, self-invoking any public method is a bad idea.