If I have the following code :
@Component
public class A{
@Transactional(propagation = Propagation.REQUIRED)
public void a(){
//logic
b();
//logic
}
@Transactional(propagation = Propagation.REQUIRED)
public void b(){
//logic
}
}
How many transactions open Spring in this code example?
It doesn't matter. When calling b() from a() it won't be going through the proxy, so any transactional attributes on b() won't be considered.
The example code has 1 transaction open if a() or b() is called through the proxy (i.e. outside of the class) and there isn't a transaction in progress already.
I add to @pablo answer the notice that in your example you cannot see the actual difference because your call your method within the same object which make @transaction behavior on the second method transparent with no effect :
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
From spring documentation: https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/transaction/annotation/Propagation.html
REQUIRED: Support a current transaction, create a new one if none exists
It only creates one transaction.
Refering to the documentation Propagation.REQUIREDsupport a current transaction, create a new one if none exists. The answer to your question is :
1 transaction, if there is no transaction when A#a() is called.
0- zero if there is already one because it will be reused.
