Spring - @Transactional - What happens in background?

Spring - @Transactional - What happens in background?

Do you ever wonder what actually happens when you annotate a method with @Transactional in Spring? Sure, you know that Spring will wrap that method in a transaction, but there may still be some lingering doubts. Fear not! In this blog post, we will dive deep into the background workings of the @Transactional annotation and provide easy-to-understand solutions to common issues. So grab your favorite beverage and let's get started!

1. The Mystery of the Proxy Class

You may have heard that Spring creates a proxy class when you use the @Transactional annotation, but what exactly is happening behind the scenes? 🤔

When you annotate a method with @Transactional, Spring generates a proxy class that wraps around your actual class. This proxy class acts as a go-between for any method calls coming from external sources.

But what about the actual class? Don't worry, it's still there! The proxy class simply intercepts the method calls and adds the necessary transactional behavior. Your actual class remains untouched.

Now, you might be wondering, how can I see Spring's created proxied class? To observe the proxy class in action, you can use debugging tools like IntelliJ IDEA or Eclipse. Set a breakpoint inside a method marked with @Transactional and inspect the object's class. You will notice that it's the generated proxy class.

2. "Self-Invocation" Mystery Unveiled

You may have come across this perplexing statement in the Spring documentation:

"Only 'external' method calls coming in through the proxy will be intercepted. This means that 'self-invocation', i.e., a method within the target object calling some other method of the target object, won't lead to an actual transaction at runtime even if the invoked method is marked with @Transactional!"

Hold on a second! Why are only external method calls under transactions, while self-invocation methods are excluded? 🤔

The reason behind this design is to prevent unnecessary transactional boundaries within your own code. When a method within the target object invokes another method of the same object, it is considered a "self-invocation." Spring avoids creating a new transaction for such invocations to prevent transactional overhead.

However, keep in mind that if you invoke a @Transactional-annotated method from another bean, outside the target object, the transactional behavior will be applied.

The Call-to-Action: Engage and Share!

Now that we've demystified the inner workings of the @Transactional annotation in Spring, it's time to put your newfound knowledge into action! Implement transactions like a pro and share this blog post with your fellow developers to help them level up their Spring skills.

If you have any more questions or want to share your own experiences, leave a comment below. Let's create a vibrant community of Spring enthusiasts ready to conquer any transactional challenge!

Happy coding! 💻🌼