How to determine the number of transactions when calling a method annotated with @Transactional from another method with the same annotation in a different class in Spring?

In Spring, the @Transactional annotation manages transactions at the proxy level. When calling a method annotated with @Transactional from another class also annotated with @Transactional, Spring creates or uses an existing transaction depending on the propagation settings.

To determine the number of transactions in such a call, consider:

• Propagation (transaction propagation behavior): by default, REQUIRED — if a transaction already exists, the method will run within it; a new one is not created.
• Call from another class: Spring proxy triggers, and transaction management occurs correctly.

For precise counting of transactions, you can use:

• Logging or debugging the transaction manager.
• Injecting a custom PlatformTransactionManager or transaction listener.
• Using AOP to intercept transaction start and end.

Example of logging transaction start:

@Component
public class TransactionLogger implements TransactionSynchronization {
    @Override
    public void beforeCommit(boolean readOnly) {
        System.out.println("Transaction begins");
    }

    @Override
    public void afterCompletion(int status) {
        System.out.println("Transaction completed");
    }
}

And registering this listener in TransactionSynchronizationManager.

Thus, when calling a method with @Transactional from another class with @Transactional, usually only one transaction will be active unless propagation is changed.