java - Spring Boot - @Async 被忽略

Question

使用 Spring Boot 1.5.2.RELEASE 和 @Async 注释似乎被忽略了。

环境设置如下:

@SpringBootApplication
@EnableAsync
public class Application extends AsyncConfigurerSupport {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Override
    public Executor getAsyncExecutor() {

        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();

        executor.setCorePoolSize(2);
        executor.setMaxPoolSize(2);
        executor.setQueueCapacity(500);
        executor.setThreadNamePrefix("async-task-");

        executor.initialize();

        return executor;
    }

    ...

...异步方法本身:

@Service
public class MyService {

    @Async
    public Future<Long> asyncTask() throws Exception {

        Long test = 1023L;

        Thread.sleep(10000);

        return new AsyncResult<>(test);
    }
}

...现在我正在尝试使用它:

@RestController
public MyController {

    @Autowired
    public MyService myService;

    @PostMapping("/test")
    public ResponseEntity<MyResponse> test() {
        return new ResponseEntity<>(
                       new MyResponse(myService
                           .asyncTask()
                           .get()), 
                       HttpStatus.OK);
    }
}

...并且 Controller 方法仍然挂起 10sec 而不是立即返回。

@Async 方法从不同的对象调用。正如它在类似问题中提到的那样，它既不是私有(private)的也不是交易的。

如何让方法异步调用？

Answer 1

你应该看看 Future#get javadoc :

Waits if necessary for the computation to complete, and then retrieves its result.

您正在通过调用 get 方法将异步方法转换为同步调用。

因此，不是调用 get，而是返回 Future。 Spring MVC 支持 future as return type :

A ListenableFuture or CompletableFuture/CompletionStage can be returned when the application wants to produce the value from a thread pool submission.

例子:

return myService.asyncTask().thenApply(r -> ResponseEntity.ok(new MyResponse(r)));