@Async not working in Spring API rest with Interfaces

Question

I'm working with @Async to stored some data in parallel in the database with hibernate. I need to do that because before saving the information to the database I need to run some task that takes several minutes. So I implemented @Async.

The issue is that @Async seems to not be working. Please find the code below:

WebConfig

@Configuration
@EnableAsync
@EnableWebMvc
public class WebConfig extends WebMvcConfigurerAdapter {

}

StudentServiceImpl:

@Autowired
RunSomeTaskService runSomeTaskService;

@Override
Transactional
public Response saveWithoutWaiting(StudentBO[] students, String username) throws Exception {
...
for (StudentBO student : students) {
    ....
    Future<Response> response = runSomeTaskService.doTasks(student);
    //Finish without waiting for doTasks().
}

@Override
    Transactional
    public Response saveWithWaiting(StudentBO[] students, String username) throws Exception {
    ...
    for (StudentBO student : students) {
        ....
        Future<Response> response = runSomeTaskService.doTasks(student);
        //Finish and wait for doTasks().
        response.get();
    }

RunSomeTaskService:

public interface RunSomeTaskService{
    @Async
    public Future<Response> doTasks(Student student);
}

RunSomeTaskServiceImpl:

public class RunSomeTaskServiceImpl extends CommonService implements RunSomeTaskService{

Student student;
@Override
    public Future<Response> doTasks(Student student) {
          Response response = new Response();
          this.student = student;
          //do Task
          return new AsyncResult<Response>(response);
       }
}

web.xml

<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
          http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    version="3.0">

    <display-name>Sample Spring Maven Project</display-name>

    <servlet>
        <servlet-name>mvc-dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring-config.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
        <async-supported>true</async-supported>
    </servlet>

    <servlet-mapping>
        <servlet-name>mvc-dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

<filter>
    <filter-name>encodingFilter</filter-name>
    <filter-class>
            org.springframework.web.filter.CharacterEncodingFilter
        </filter-class>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>UTF-8</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>encodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  <filter>
    <filter-name>jwtTokenAuthFilter</filter-name>
    <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>jwtTokenAuthFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>

spring.config.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:util="http://www.springframework.org/schema/util" 
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
  http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
  http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd
  http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
  http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

    <context:annotation-config  />
    <context:component-scan base-package="com.app.controller" />
    <tx:annotation-driven transaction-manager="transactionManager"/>
    <mvc:annotation-driven />

    <bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        ...
    </bean>

    <bean id="mailSender" class="org.springframework.mail.javamail.JavaMailSenderImpl">
...
    </bean>


    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="annotatedClasses">
            <list>
                <value>//every model generated with Hibernate</value>
            </list>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
                <prop key="hibernate.show_sql">true</prop>
            </props>
        </property>
    </bean>

    <bean id="transactionManager"
        class="org.springframework.orm.hibernate5.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory" />
    </bean>

    <bean id="persistenceExceptionTranslationPostProcessor"
        class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />

    <bean id="studentService" class="com.app.services.StudentServiceImpl"></bean>
    <bean id="studentDao" class="com.app.dao.StudentDaoImpl"></bean>
    ...

    <bean id="jwtTokenAuthFilter" class="com.app.security.JWTTokenAuthFilter" />       
</beans>

So, could you please help me to understand why @Async is not working?

UPDATE: @Async is now working, but I'm not getting the expected results.

For the case, that I have to wait for the result (sync case) CompletableFuture.get() is not waiting for the response and I'm getting and error:

My code:

CompletableFuture<Response> res = extractDataService.doTask(student);

The error:

org.hibernate.HibernateException: Illegal attempt to associate a collection with two open sessions. Collection : <unknown>
Collection contents: [[]]
        at org.hibernate.collection.internal.AbstractPersistentCollection.setCurrentSession(AbstractPersistentCollection.java:627)
        at org.hibernate.event.internal.OnUpdateVisitor.processCollection(OnUpdateVisitor.java:46)
        at org.hibernate.event.internal.AbstractVisitor.processValue(AbstractVisitor.java:104)
        at org.hibernate.event.internal.AbstractVisitor.processValue(AbstractVisitor.java:65)
        at org.hibernate.event.internal.AbstractVisitor.processEntityPropertyValues(AbstractVisitor.java:59)
        at org.hibernate.event.internal.AbstractVisitor.process(AbstractVisitor.java:126)
        at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.performUpdate(DefaultSaveOrUpdateEventListener.java:293)
        at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsDetached(DefaultSaveOrUpdateEventListener.java:227)
        at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:92)
        at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:73)
        at org.hibernate.internal.SessionImpl.fireSaveOrUpdate(SessionImpl.java:648)
        at org.hibernate.internal.SessionImpl.saveOrUpdate(SessionImpl.java:640)
        at org.hibernate.internal.SessionImpl.saveOrUpdate(SessionImpl.java:635)
        at com.app.dao.CommonDaoImpl.addOrUpdate(CommonDaoImpl.java:28)
        at com.app.services.ExtractDataServiceImpl.doExtraction(ExtractDataServiceImpl.java:361)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:302)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
        at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
        at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
        at org.springframework.aop.interceptor.AsyncExecutionInterceptor$1.call(AsyncExecutionInterceptor.java:108)
        at org.springframework.aop.interceptor.AsyncExecutionAspectSupport$CompletableFutureDelegate$1.get(AsyncExecutionAspectSupport.java:237)
        at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

When I don't have to wait and I execute several cases in Async way I get:

12:17:44.040 [DEMO-4] DEBUG o.h.r.t.b.j.i.JdbcResourceLocalTransactionCoordinatorImpl - JDBC transaction marked for rollback-only (exception provided for stack trace)
java.lang.Exception: exception just for purpose of providing stack trace
        at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.markRollbackOnly(JdbcResourceLocalTransactionCoordinatorImpl.java:265) [hibernate-core-5.0.6.Final.jar:5.0.6.Final]
        at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCallback(JdbcResourceLocalTransactionCoordinatorImpl.java:156) [hibernate-core-5.0.6.Final.jar:5.0.6.Final]
        at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$100(JdbcResourceLocalTransactionCoordinatorImpl.java:38) [hibernate-core-5.0.6.Final.jar:5.0.6.Final]
        at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:231) [hibernate-core-5.0.6.Final.jar:5.0.6.Final]
        at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:65) [hibernate-core-5.0.6.Final.jar:5.0.6.Final]
        at org.springframework.orm.hibernate5.HibernateTransactionManager.doCommit(HibernateTransactionManager.java:581) [spring-orm-4.2.4.RELEASE.jar:4.2.4.RELEASE]
        at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:761) [spring-tx-4.2.4.RELEASE.jar:4.2.4.RELEASE]
        at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:730) [spring-tx-4.2.4.RELEASE.jar:4.2.4.RELEASE]
        at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:485) [spring-tx-4.2.4.RELEASE.jar:4.2.4.RELEASE]
        at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:291) [spring-tx-4.2.4.RELEASE.jar:4.2.4.RELEASE]
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) [spring-tx-4.2.4.RELEASE.jar:4.2.4.RELEASE]
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
        at org.springframework.aop.interceptor.AsyncExecutionInterceptor$1.call(AsyncExecutionInterceptor.java:108) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
        at org.springframework.aop.interceptor.AsyncExecutionAspectSupport$CompletableFutureDelegate$1.get(AsyncExecutionAspectSupport.java:237) [spring-aop-4.2.4.RELEASE.jar:4.2.4.RELEASE]
        at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1590) [na:1.8.0_171]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_171]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_171]
        at java.lang.Thread.run(Thread.java:748) [na:1.8.0_171]
12:17:44.043 [DEMO-4] DEBUG o.s.o.h.HibernateTransactionManager - Initiating transaction rollback after commit exception
org.hibernate.AssertionFailure: null id in com.app.model.FieldValue entry (don't flush the Session after an exception occurs)

Answer 1

Just use:

servlet.setAsyncSupported(true);

For Example

public class WebAppInitializer implements WebApplicationInitializer {
    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
        ctx.register(WebConfig.class);
        ctx.setServletContext(servletContext);
        ServletRegistration.Dynamic servlet = servletContext.addServlet("dispatcher",
            new DispatcherServlet(ctx));
        servlet.setLoadOnStartup(1);
        servlet.addMapping("/");
        servlet.setAsyncSupported(true); //Servlets were marked as supporting async
        // For CORS Pre Filght Request
        servlet.setInitParameter("dispatchOptionsRequest", "true");
    }
}

Answer 2

More Sophisticated way would be to implement AsyncConfigurer and set the AsyncExecutor to threadPoolTaskExecutor.

Sample Code below

@Configuration
@EnableAsync(proxyTargetClass=true) //detects @Async annotation
public class AsyncConfig implements AsyncConfigurer {

 public Executor threadPoolTaskExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(10); // create 10 Threads at the time of initialization
        executor.setQueueCapacity(10); // queue capacity
        executor.setMaxPoolSize(25); // if queue is full, then it will create new thread and go till 25
        executor.setThreadNamePrefix("DEMO-");
        executor.initialize();//Set up the ExecutorService.
        return executor;
    }

    @Override
    public Executor getAsyncExecutor() {
        return threadPoolTaskExecutor();
    }

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

} 

The above configuration will detect @Async annotation wherever mentioned