@EventListener with @Async in Spring

Question

Trying to enable async event handling combining the @Async and @EventListener annotations, but I still see that the listener is running in the publishing thread.

The example you can find here:

@SpringBootApplication @EnableAsync class AsyncEventListenerExample {  static final Logger logger = LoggerFactory.getLogger(AsyncEventListenerExample.class);  @Bean TaskExecutor taskExecutor() {     return new SimpleAsyncTaskExecutor(); }   static class MedicalRecordUpdatedEvent {      private String id;      public MedicalRecordUpdatedEvent(String id) {         this.id = id;     }      @Override     public String toString() {         return "MedicalRecordUpdatedEvent{" +                 "id='" + id + '\'' +                 '}';     } }  @Component static class Receiver {      @EventListener     void handleSync(MedicalRecordUpdatedEvent event) {         logger.info("thread '{}' handling '{}' event", Thread.currentThread(), event);     }      @Async     @EventListener     void handleAsync(MedicalRecordUpdatedEvent event) {         logger.info("thread '{}' handling '{}' event", Thread.currentThread(), event);     }  }  @Component static class Producer {      private final ApplicationEventPublisher publisher;      public Producer(ApplicationEventPublisher publisher) {         this.publisher = publisher;     }      public void create(String id) {         publisher.publishEvent(new MedicalRecordUpdatedEvent(id));     }      @Async     public void asynMethod() {         logger.info("running async method with thread '{}'", Thread.currentThread());     } }  } 

and my test case:

@RunWith(SpringRunner.class) @SpringBootTest(classes = AsyncEventListenerExample.class) public class AsyncEventListenerExampleTests {  @Autowired Producer producer;  @Test public void createEvent() throws InterruptedException {      producer.create("foo");      //producer.asynMethod();       // A chance to see the logging messages before the JVM exists.     Thread.sleep(2000);  } } 

However in logs I see that both @EventListeners run in the main thread.

2016-05-12 08:52:43.184  INFO 18671 --- [           main] c.z.e.async2.AsyncEventListenerExample   : thread 'Thread[main,5,main]' handling 'MedicalRecordUpdatedEvent{id='foo'}' event 2016-05-12 08:52:43.186  INFO 18671 --- [           main] c.z.e.async2.AsyncEventListenerExample   : thread 'Thread[main,5,main]' handling 'MedicalRecordUpdatedEvent{id='foo'}' event 

The async infrastructure is initialised with @EnableAsync with an asynchronous TaskExecutor.

Not sure what I am doing wrong. Could you help?

Thanks.

Using Spring Boot 1.4.2.M2, so Spring 4.3.0.RC1

Answer 1

There was a regression in Spring Framework 4.3.0.RC1 that leads to that very issue you're having. If you use the SNAPSHOT, your project runs fine.

Answer 2

onTicketUpdatedEvent runs in also main Thread with Spring Framework 4.2.4 Release as follows. But it runs in SimpleAsyncTaskExecutor if AsyncConfigurer is not implemented.

@EnableAsync(proxyTargetClass = true) @Component @Slf4j public class ExampleEventListener implements AsyncConfigurer {      @Async     @EventListener     public void onTicketUpdatedEvent(TicketEvent ticketEvent) {         log.debug("received ticket updated event");     }      @Override     public Executor getAsyncExecutor() {         ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();         executor.setMaxPoolSize(100);         executor.initialize();         return executor;     }      @Override     public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {         return null;     } }