Spring @Async Not Working

Question

An @Async method in a @Service-annotated class is not being called asynchronously - it's blocking the thread.

I've got <task: annotation-driven /> in my config, and the call to the method is coming from outside of the class so the proxy should be being hit. When I step through the code, the proxy is indeed hit, but it doesn't seem to go anywhere near any classes related to running in a task executor.

I've put breakpoints in AsyncExecutionInterceptor and they never get hit. I've debugged into AsyncAnnotationBeanPostProcessor and can see advice getting applied.

The service is defined as an interface (with the method annotated @Async there for good measure) with the implementation's method annotated @Async too. Neither are marked @Transactional.

Any ideas what may have gone wrong?

-=UPDATE=-

Curiously, it works only when I have my task XML elements in my app-servlet.xml file, and not in my app-services.xml file, and if I do my component scanning over services from there too. Normally I have one XML file with only controllers in it (and restrict the component-scan accordingly), and another with services in it (again with a component-scan restricted such that it doesn't re-scan the controllers loaded in the other file).

app-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans" 
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns:jee="http://www.springframework.org/schema/jee" 
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:webflow="http://www.springframework.org/schema/webflow-config" 
xmlns:task="http://www.springframework.org/schema/task"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd
    http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
    http://www.springframework.org/schema/task
    http://www.springframework.org/schema/task/spring-task-3.0.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
    http://www.springframework.org/schema/jee 
    http://www.springframework.org/schema/jee/spring-jee-3.0.xsd"
>
<task:annotation-driven executor="executor" />
<task:executor id="executor" pool-size="7"/>

<!-- Enable controller annotations -->
<context:component-scan base-package="com.package.store">
    <!-- <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller" /> -->
</context:component-scan>

<tx:annotation-driven/>
<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
    <property name="sessionFactory" ref="sessionFactory"/>
</bean>

<mvc:annotation-driven conversion-service="conversionService" />

<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix" value="/WEB-INF/jsp/" />
    <property name="suffix" value=".jsp" />
</bean>

app-services.xml (doesn't work when specified here)

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" 
xmlns:context="http://www.springframework.org/schema/context" xmlns:task="http://www.springframework.org/schema/task"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/task
        http://www.springframework.org/schema/task/spring-task-3.0.xsd">

    <!-- Set up Spring to scan through various packages to find annotated classes -->
    <context:component-scan base-package="com.package.store">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller" />
    </context:component-scan>

    <task:annotation-driven executor="han" />
    <task:executor id="han" pool-size="6"/>
    ...

Am I missing something glaringly obvious in my configuration, or is there some subtle interplay between config elements going on?

Answer 1

1. Try adding proxy-target-class="true" to all <*:annotation-driven/> elements that support this attribute.
2. Check if your method annotated with @Async is public.

Answer 2

With the help of this excellent answer by Ryan Stewart, I was able to figure this out (at least for my specific problem).

In short, the context loaded by the ContextLoaderListener (generally from applicationContext.xml) is the parent of the context loaded by the DispatcherServlet (generally from *-servlet.xml). If you have the bean with the @Async method declared/component-scanned in both contexts, the version from the child context (DispatcherServlet) will override the one in the parent context (ContextLoaderListener). I verified this by excluding that component from component scanning in the *-servlet.xml -- it now works as expected.

Answer 3

I realized following the tutorial async-method tutorial code that my issue source was: the bean with the annotated @Async method was not being created wrapped in a proxy. I started digging and realized that there was a message saying

Bean 'NameOfTheBean' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)

You can see here responses about this issue and its basically that BeanPostProcessors are required by every Bean, so every bean injected here and its dependencies will be excluded to be processed later by other BeanPostProcessors, because it corrupted the life cycle of beans. So identify which is the BeanPostProcessor that is causing this and dont use or create beans inside of it.

In my case i had this configuration

@EnableWs
@Configuration
public class WebServiceConfig extends WsConfigurerAdapter {

    @Autowired
    private Wss4jSecurityInterceptor securityInterceptor;

    @Autowired
    private DefaultPayloadLoggingInterceptor payloadLoggingInterceptor;

    @Override
    public void addInterceptors(List<EndpointInterceptor> interceptors) {
        interceptors.add(securityInterceptor);
        interceptors.add(payloadLoggingInterceptor);
    }
}

WsConfigurerAdapter is actually a BeanPostProcessor and you realize it because there is always a pattern: @Configuration that extends classes and override some of it functions to install or tweak beans involved in some non functional features, like web service or security.

In the aforementioned example you have to override the addInterceptors and added interceptors beans, so if you are using some annotation like @Async inside DefaultPayloadLoggingInterceptor it wont work. What is the solution? Get ride of WsConfigurerAdapter to start. After digging a bit i realized a class named PayloadRootAnnotationMethodEndpointMapping at the end was which had all valid interceptors, so i did it manually insted of overriding a function.

@EnableWs
@Configuration
public class WebServiceConfig {

    @Autowired
    private Wss4jSecurityInterceptor securityInterceptor;

    @Autowired
    private DefaultPayloadLoggingInterceptor payloadLoggingInterceptor;

    @Autowired
    public void setupInterceptors(PayloadRootAnnotationMethodEndpointMapping endpointMapping) {
        EndpointInterceptor[] interceptors = {
                securityInterceptor,
                payloadLoggingInterceptor
        };

        endpointMapping.setInterceptors(interceptors);
    }
}

So this will be run after all BeanPostProcessor have done their job. The setupInterceptors function will run when that party is over and install the interceptors beans. This use case may be extrapolated to cases like Security.

Conclusions:

• If you are using a @Configuration extending from some class that runs some given functions automatically and you override them, you are probably inside of a BeanPostProcessor, so dont inject beans there and try to use AOP behaviour, because it wont work, and you will see Spring tells it to you with the beforementioned message in the console. In those cases dont use beans but objects (using the new clause).
• If you need to use beans digg about which class is carrying the beans you want to setup at the end, @Autowired it and add those beans like i did before.

I hope this may save some time for you.

Answer 4

You need 3 lines of code for Async to work

1. in applicationContext.xml
2. At class level @EnableAsync
3. @Async at method level

@Service @EnableAsync public myClass {

@Async public void myMethod(){

}

Answer 5

@Async can not be used in conjunction with lifecycle callbacks such as @PostConstruct. To asynchonously initialize Spring beans you currently have to use a separate initializing Spring bean that invokes the @Async annotated method on the target then.

public class SampleBeanImpl implements SampleBean {

  @Async
  void doSomething() { … }
}


public class SampleBeanInititalizer {

  private final SampleBean bean;

  public SampleBeanInitializer(SampleBean bean) {
    this.bean = bean;
  }

  @PostConstruct
  public void initialize() {
    bean.doSomething();
  }
}

source

Answer 6

For me the solution was to add @EnableAsync on my @Configuration annotated class:

@Configuration
@ComponentScan("bla.package")
@EnableAsync
public class BlaConfiguration {

}

Now the class in package bla.package which has @Async annotated methods can really have them called asynchronously.