Spring Boot REST API: How to Properly Handle Concurrent Requests with @Async and @Transactional?
I'm developing a Spring Boot REST API (version 2.5.4) that processes multiple incoming requests concurrently. I'm using `@Async` to allow methods to run in a separate thread, which is crucial for performance when processing large datasets. However, I'm encountering unexpected behavior when these methods involve database transactions. For example, I have a method annotated with `@Async` that fetches data from the database and processes it: ```java @Async @Transactional public CompletableFuture<MyData> processData(String id) { MyData data = myRepository.findById(id); // Process data... return CompletableFuture.completedFuture(data); } ``` While this seems straightforward, I'm noticing that when multiple requests hit this endpoint, I'm getting a `TransactionRequiredException` intermittently, particularly when multiple threads are trying to access the same entity simultaneously. I've tried wrapping the `@Async` method call inside a `@Transactional` service method, but that didn't resolve the issue. Additionally, I am using a thread pool executor configured in my application: ```java @Bean public Executor taskExecutor() { ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); executor.setCorePoolSize(5); executor.setMaxPoolSize(10); executor.setQueueCapacity(100); executor.setThreadNamePrefix("AsyncThread-"); executor.initialize(); return executor; } ``` Could the issue be related to how Spring manages transactions in conjunction with asynchronous processing? What would be the best practice to ensure that the method can handle concurrent requests without running into transaction issues? Any insights would be greatly appreciated!