Why is my Spring @Async bean method not being executed asychronously?

Question

I have a Springboot application and I'm trying to execute an asynchronous method on a bean class inside a controller method. The problem is that my @Async method is not being executed asynchronously. Execution is halted until the method completes.

Can anyone tell me what I'm missing?

Here is my application class:

@SpringBootApplication
@EnableAsync
public class Application {

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

    @Bean
    public EmbeddedServletContainerFactory servletContainer() {
        TomcatEmbeddedServletContainerFactory factory = new TomcatEmbeddedServletContainerFactory();
        factory.addConnectorCustomizers(new TomcatConnectorCustomizer() {

            @Override
            public void customize(Connector connector) {

                connector.setPort(9000);
                connector.setAsyncTimeout(60000);
            }
        });
        return factory;
    }
 }

Here is my bean class:

public class LongProcess {

    @Async
    public Future<String> call() {
        try {
            System.out.println("Sleeping now...");
            Thread.sleep(10000);
            return new AsyncResult<String>("Hey");
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return null;
        }
    }

}

My configuration class:

@Configuration
@EnableAsync
public class LongProcessConfiguration implements AsyncConfigurer {

    @Bean
    public LongProcess longProcessBean() {
        return new LongProcess();
    }

    @Override
    public Executor getAsyncExecutor() {
        ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
        taskExecutor.setMaxPoolSize(10);
        taskExecutor.setThreadNamePrefix("LULExecutor-");
        taskExecutor.initialize();
        return taskExecutor;
    }

    @Override
    public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
        return new SimpleAsyncUncaughtExceptionHandler();
    }

}

My controller method:

@RequestMapping("/utilities/longProcess")
    public String longProcess() {

        System.out.println("Starting long process...");
        CsvFileDifferConfiguration context = new CsvFileDifferConfiguration();
        LongProcess process = context.longProcessBean();
        Future<String> result = process.call();
        System.out.println("Done!");
        return "{success: 1}";

    }

This request unfortunately does not return immediately (I don't care about the result). The method is called successfully, but not in the background. Any idea what I might be missing?

As a test, if I change the controller method to wait for the result, the wait block is never entered:

@RequestMapping("/utilities/longProcess")
    public String longProcess() throws InterruptedException {

        System.out.println("Starting long process...");
        CsvFileDifferConfiguration context = new CsvFileDifferConfiguration();
        LongProcess process = context.longProcessBean();
        Future<String> result = process.call();
        while (!(result.isDone())) {
            Thread.sleep(1); //10-millisecond pause between each check
            System.out.println("Waiting for Long Process...");
        }
        System.out.println("Done!");
        return "{success: 1}";

    }

Answer 1

You have a mistake for the CDI usage. If you manage your object using Spring Container you have to get deal just with ApplicationContext or its abilities like @Autowired.

The code

CsvFileDifferConfiguration context = new CsvFileDifferConfiguration();

is wrong.

Since you define your LongProcess as a @Bean you can just inject it to your @Controller:

@Autowired
privete LongProcess process;

and use it as before.

Using objects directly (e.g. new) loses the dependency injection features.

Read more Spring Docs, please.