👀 Views: 2 💬 Answers: 1 📅 Created: 2025-06-04

java spring-boot completablefuture asynchronous Java

I'm stuck on something that should probably be simple. I'm working on a personal project and I recently integrated `CompletableFuture` into my Spring Boot application to handle asynchronous processing. However, I am encountering an unexpected behavior where my CompletableFuture occasionally completes exceptionally even though the underlying task completes successfully. Here's a simplified version of my code: ```java @Service public class MyAsyncService { @Async public CompletableFuture<String> processTask() { // Simulating some processing work try { Thread.sleep(2000); } catch (InterruptedException e) { Thread.currentThread().interrupt(); return CompletableFuture.completedFuture("Task interrupted"); } return CompletableFuture.completedFuture("Task completed"); } } ``` In my controller, I call this service as follows: ```java @RestController public class MyController { private final MyAsyncService myAsyncService; public MyController(MyAsyncService myAsyncService) { this.myAsyncService = myAsyncService; } @GetMapping("/startTask") public ResponseEntity<String> startTask() { CompletableFuture<String> future = myAsyncService.processTask(); future.exceptionally(ex -> { System.out.println("Error: " + ex.getMessage()); return "Error occurred"; }); return ResponseEntity.ok("Task started"); } } ``` Occasionally, I see the following output in my logs: ``` Error: Task interrupted ``` But I ensure that it should not be interrupted under normal circumstances. I suspect it might be related to thread management, especially since I haven't configured an `Executor` bean for `@Async`. My application is running on Spring Boot 2.6.4. I've tried adding an `Executor` bean like this: ```java @Bean public Executor taskExecutor() { ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor(); executor.setCorePoolSize(5); executor.setMaxPoolSize(10); executor.setQueueCapacity(100); executor.initialize(); return executor; } ``` However, I still see the same intermittent behavior. Is there something I might be missing regarding the configuration or usage of CompletableFuture with Spring's `@Async`? Any insights or debugging tips would be greatly appreciated! Am I missing something obvious? This issue appeared after updating to Java LTS.