Mastering Spring & MSA Transactions – Part 12: When Transactions “Don’t Work”: Common Causes and Debugging Tips

You’ve configured your @Transactional settings—propagation, isolation, rollback rules—and verified everything in your code. Yet, sometimes you find a transaction isn’t firing, or a rollback isn’t happening. Why? This chapter examines three frequent culprits and some handy troubleshooting approaches.

1) Most Common Causes

1.1) Bean Not in Spring’s Scope → No Proxy Created

• Out of @ComponentScan range: If your class is outside the packages that Spring scans, Spring won’t manage that class as a bean—so it can’t create a transaction proxy.
• Manually instantiated (via new): If you instantiate an object on your own, Spring has no chance to wrap it in a proxy.
• Result: @Transactional does nothing because there’s no AOP intercepting calls.

Example:

// Suppose you do this in code:
OrderService service = new OrderService(); 
// This is a plain instance, no Spring proxy -> no transaction logic
service.placeOrder(...);

To fix this, ensure you annotate it as a Spring bean (@Service, etc.) and keep it in the scanned package structure. Let Spring handle object creation and injection.

1.2) Method Is private/final/static → Can’t Be Proxied

• private methods can’t be overridden even by CGLIB subclassing; JDK proxies only intercept public interface methods.
• final methods also block CGLIB from overriding them.
• static is purely a class-level function with no instance context to wrap.

If you put @Transactional on any such method, it won’t be intercepted by the proxy—thus the transaction logic never triggers. If you truly need a transaction scope for that code, place it in a public method, or in a separate bean that calls it from outside.

1.3) Internal Calls: Proxy Bypass

• From the previous discussion on how AOP proxies work, calling another method in the same class (e.g., this.helperMethod()) skips the proxy, preventing the second method’s transaction settings (e.g., REQUIRES_NEW) from activating.
• If you want a separate transaction in a sub-operation, you typically must call it from a different bean or some external injection method (like self-injection or AspectJ advanced weaving).

Typical Example:

@Service
public class OrderService {
    @Transactional
    public void placeOrder(...) {
        // This method is covered by a transaction
        this.auditLog(...); 
        // Internal call => no new transaction triggered
    }

    @Transactional(propagation=Propagation.REQUIRES_NEW)
    public void auditLog(...) {
        // Expectation: brand-new transaction
        // Reality: call is internal, bypasses proxy
    }
}

2) Solutions or Debugging Tips

1. Check If the Proxy Is Created
   • Enable DEBUG logs for org.springframework.aop or org.springframework.transaction: look for “Creating proxy for bean…” or “Advised methods:” messages. If you don’t see them, that bean isn’t being proxied.
   • Tools like Spring Boot Actuator can show if a bean is actually a proxy class.
2. Verify @ComponentScan / @SpringBootApplication Ranges
   • Confirm the bean’s package is included in scanning. A frequent mistake is placing classes outside the “main” scanned package, so they aren’t recognized as beans.
3. Public Methods for Transaction, or Move Code to Another Bean
   • If a method must get its own transaction, ensure it’s public and externally called. If you keep it private or final, Spring can’t advise it.
   • If you’re calling from the same class, consider splitting the logic into a separate Service so calls become external and pass through the second bean’s proxy.
4. Check for Self-Invocation
   • If you do this.someMethod() internally, it never crosses the proxy boundary. If you want a different transaction scope, do a separate bean call or advanced solutions like self-injection or AspectJ.

Conclusion

When transaction settings don’t seem to apply, the usual suspects are:

• Bean never got proxied, because it’s outside scanning or manually instantiated.
• Method is private/final/static, so the proxy can’t intercept it.
• Internal calls bypass the proxy, so new transaction rules or readOnly settings won’t kick in.

Debug by checking proxy creation logs, ensuring it’s a public method inside a Spring-managed bean, and confirm calls are made from outside the bean if you need a distinct transaction scope. If advanced scenarios arise, advanced AOP techniques (AspectJ, self-reference) or separate beans are your best bet.

Understanding these core proxy limitations will help you quickly spot why @Transactional “isn’t working” and guide you to the right fix—whether that’s adjusting your package structure, changing method signatures, or refactoring code to use external bean calls where you truly want a separate transaction.