Hot questions for Spring Transaction Management

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Question:

I'm new to Spring and I'm wondering if its possible to use numerous transaction managers in the same application?

I have two data access layers - one for both of the databases. I'm wondering, how do you go about using one transaction managers for one layer and different transaction manager for the other layer. I don't need to perform transactions across both databases - yet. But I do need perform transactions on each database individually. I've created an image to help outline my problem:

Here is my application context configuration:

<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: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">

    <context:component-scan base-package="cheetah.repositories" />
    <tx:annotation-driven />

    <bean id="entityManagerFactory"
        class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean">
        <property name="persistenceUnitName" value="accounts" />
    </bean>

    <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />

    <bean id="transactionManager"
        class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory" />
    </bean>

</beans>

Here is an example that uses this configuration:

@Repository
public class JpaAccountRepository implements AccountRepository {

    @PersistenceContext(unitName = "cheetahAccounts")
    private EntityManager accountManager;

    @Override
    @Transactional
    public Account findById(long id) {

        Account account = accountManager.find(Account.class, id);
        return account;
    }
}

So for the account repository, I want to use an entity manager factory with the persistence unit set to accounts. However, with my BusinessData Repository, I want to use an entity manager factory with a different persistence unit. Since I can only define one transaction manager bean, how can I go about using different transaction managers for the different repositories?

Thanks for any help.


Answer:

Where you use a @Transactional annotation, you can specify the transaction manager to use by adding an attribute set to a bean name or qualifier. For example, if your application context defines multiple transaction managers with qualifiers:

<bean id="transactionManager1"
    class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory1" />
    <qualifier value="account"/>
</bean>

<bean id="transactionManager2"
    class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory2" />
    <qualifier value="businessData"/>
</bean>

You can use the qualifier to specify the transaction manager to use:

public class TransactionalService {

    @Transactional("account")
    public void setSomethingInAccount() { ... }

    @Transactional("businessData")
    public void doSomethingInBusinessData() { ... }
}

Question:

I'm using Spring / Spring-data-JPA and find myself needing to manually force a commit in a unit test. My use case is that I am doing a multi-threaded test in which I have to use data that is persisted before the threads are spawned.

Unfortunately, given that the test is running in a @Transactional transaction, even a flush does not make it accessible to the spawned threads.

   @Transactional   
   public void testAddAttachment() throws Exception{
        final Contract c1 = contractDOD.getNewTransientContract(15);
        contractRepository.save(c1);

        // Need to commit the saveContract here, but don't know how!                
        em.getTransaction().commit();

        List<Thread> threads = new ArrayList<>();
        for( int i = 0; i < 5; i++){
            final int threadNumber = i; 
            Thread t =  new Thread( new Runnable() {
                @Override
                @Transactional
                public void run() {
                    try {
                        // do stuff here with c1

                        // sleep to ensure that the thread is not finished before another thread catches up
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            });
            threads.add(t);
            t.start();
        }

        // have to wait for all threads to complete
        for( Thread t : threads )
            t.join();

        // Need to validate test results.  Need to be within a transaction here
        Contract c2 = contractRepository.findOne(c1.getId());
    }

I've tried using the entity manager to, but get an error message when I do:

org.springframework.dao.InvalidDataAccessApiUsageException: Not allowed to create transaction on shared EntityManager - use Spring transactions or EJB CMT instead; nested exception is java.lang.IllegalStateException: Not allowed to create transaction on shared EntityManager - use Spring transactions or EJB CMT instead
    at org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:293)
    at org.springframework.orm.jpa.aspectj.JpaExceptionTranslatorAspect.ajc$afterThrowing$org_springframework_orm_jpa_aspectj_JpaExceptionTranslatorAspect$1$18a1ac9(JpaExceptionTranslatorAspect.aj:33)

Is there any way to commit the transaction and continue it? I have been unable to find any method that allows me to call a commit().


Answer:

I had a similar use case during testing hibernate event listeners which are only called on commit.

The solution was to wrap the code to be persistent into another method annotated with REQUIRES_NEW. (In another class) This way a new transaction is spawned and a flush/commit is issued once the method returns.

Keep in mind that this might influence all the other tests! So write them accordingly or you need to ensure that you can clean up after the test ran.

Question:

I have a method that has the propagation = Propagation.REQUIRES_NEW transactional property:

@Transactional(propagation = Propagation.REQUIRES_NEW)
public void createUser(final UserBean userBean) {
    //Some logic here that requires modification in DB
}

This method can be called multiple times simultaneously, and for every transaction if an error occurs than it's rolled back (independently from the other transactions).

The problem is that this might force Spring to create multiple transactions, even if another one is available, and may cause some performance problems.


Java doc of propagation = Propagation.REQUIRED says: Support a current transaction, create a new one if none exists.

This seems to solve the performance problem, doesn't it?

What about the rollback issue ? What if a new method call rolls back while using an existing transaction ? won't that rollback the whole transaction even the previous calls ?

[EDIT] I guess my question wasn't clear enough:

We have hundreds of clients connected to our server.

For each client we naturally need to send a feedback about the transaction (OK or exception -> rollback).

My question is: if I use REQUIRED, does it mean only one transaction is used, and if the 100th client encounters a problem the 1st client's transaction will rollback as well ?


Answer:

Using REQUIRES_NEW is only relevant when the method is invoked from a transactional context; when the method is invoked from a non-transactional context, it will behave exactly as REQUIRED - it will create a new transaction.

That does not mean that there will only be one single transaction for all your clients - each client will start from a non-transactional context, and as soon as the the request processing will hit a @Transactional, it will create a new transaction.

So, with that in mind, if using REQUIRES_NEW makes sense for the semantics of that operation - than I wouldn't worry about performance - this would textbook premature optimization - I would rather stress correctness and data integrity and worry about performance once performance metrics have been collected, and not before.

On rollback - using REQUIRES_NEW will force the start of a new transaction, and so an exception will rollback that transaction. If there is also another transaction that was executing as well - that will or will not be rolled back depending on if the exception bubbles up the stack or is caught - your choice, based on the specifics of the operations. Also, for a more in-depth discussion on transactional strategies and rollback, I would recommend: «Transaction strategies: Understanding transaction pitfalls», Mark Richards.

Question:

I am trying to configure JSF+Spring+hibernate and I'm tying to run a test but when I use this "tx:annotation-driven" on my application-context.xml file, I get this error:

The matching wildcard is strict, but no declaration can be found for element 'tx:annotation-driven'

Here is my application-context.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:aop="http://www.springframework.org/schema/aop"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"

       xsi:schemaLocation="http://www.springframework.org/schema/beans 
          http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
          http://www.springframework.org/schema/aop 
          http://www.springframework.org/schema/aop/spring-aop-2.5.6.xsd
          http://www.springframework.org/schema/context 
          http://www.springframework.org/schema/context/spring-context-2.5.6.xsd
          http://www.springframework.org/schema/tx 
          http://www.springframework.org/schema/tx/spring-tx-2.5.6.xsd
" xmlns:tool="http://www.springframework.org/schema/tool">
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
        <property name="driverClassName" value="oracle.jdbc.OracleDriver"/>
        <property name="url" value="jdbc:oracle:thin:@192.168.56.101:1521:Gpsi"/>
        <property name="username" value="omar"/>
        <property name="password" value="omar"/>
    </bean>

    <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
       <property name="dataSource" ref="dataSource"/>
       <property name="annotatedClasses">
            <list>
                <value>om.mycompany.model.Course</value>
                <value>om.mycompany.model.Student</value>
                <value>om.mycompany.model.Teacher</value>
            </list>
       </property>
       <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.OracleDialect</prop>
            </props>
       </property>

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

    <context:annotation-config/>
    <context:component-scan base.package="com.mmycompany"/>
</beans>

and here is my CourseServiceImplTest. I have still not implemented the tests:

public class CourseServiceImplTest {

    private static ClassPathXmlApplicationContext context;
    private static CourseService courseService;
    public CourseServiceImplTest() {
    }

    @BeforeClass
    public static void setUpClass() throws Exception {
        context=new ClassPathXmlApplicationContext("application-context.xml");
        courseService=(CourseService) context.getBean("courseService");
    }

    @AfterClass
    public static void tearDownClass() throws Exception {
        context.close();
    }

    @Before
    public void setUp() {
    }

    @After
    public void tearDown() {
    }

    /**
     * Test of getAllCourses method, of class CourseServiceImpl.
     */
    @Test
    public void testGetAllCourses() {
        System.out.println("getAllCourses");
        CourseServiceImpl instance = new CourseServiceImpl();
        List expResult = null;
        List result = instance.getAllCourses();
        assertEquals(expResult, result);
        // TODO review the generated test code and remove the default call to fail.
        fail("The test case is a prototype.");
    }

    /**
     * Test of getCourse method, of class CourseServiceImpl.
     */
    @Test
    public void testGetCourse() {
        System.out.println("getCourse");
        Integer id = null;
        CourseServiceImpl instance = new CourseServiceImpl();
        Course expResult = null;
        Course result = instance.getCourse(id);
        assertEquals(expResult, result);
        // TODO review the generated test code and remove the default call to fail.
        fail("The test case is a prototype.");
    }

and here is the CourseServiceImpl:

@Service("courseService")
@Transactional
public class CourseServiceImpl implements CourseService{

    @Autowired
    private SessionFactory sessionFactory;
    @Override
    public List<Course> getAllCourses() {
        return sessionFactory.getCurrentSession().createQuery("from Course").list();    
    }

    @Override
    public Course getCourse(Integer id) {
        return (Course) sessionFactory.getCurrentSession().get(Course.class, id);
    }

    @Override
    public void save(Course course) {
       sessionFactory.getCurrentSession().saveOrUpdate(course);
    }

}

Answer:

You have some errors in your appcontext.xml:

  • Use *-2.5.xsd

    xsi:schemaLocation="http://www.springframework.org/schema/beans 
      http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
      http://www.springframework.org/schema/aop 
      http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
      http://www.springframework.org/schema/context 
      http://www.springframework.org/schema/context/spring-context-2.5.xsd
      http://www.springframework.org/schema/tx 
      http://www.springframework.org/schema/tx/spring-tx-2.5.xsd"
    
  • Typos in tx:annotation-driven and context:component-scan (. instead of -)

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

Question:

I've been doing some research around the performance of read-only versus read-write database transactions. The MySQL server is remote across a slow VPN link so it's easy for me to see differences between the transaction types. This is with connection pooling which I know is working based on comparing 1st versus 2nd JDBC calls.

When I configure the Spring AOP to use a read-only transaction on my DAO call, the calls are 30-40% slower compared to read-write:

<!-- slower -->
<tx:method name="find*" read-only="true" propagation="REQUIRED" />
...
// slower
@Transaction(readOnly = true)

Versus:

<!-- faster -->
<tx:method name="find*" read-only="false" propagation="REQUIRED" />
...
// faster
@Transaction

Looking at tcpdump, it seems like the read-only transaction is doing more back and forth talking to MySQL. Here's the read-only dump versus read-write.

  1. Can anyone explain why the read-only calls are taking longer. Is this expected?

  2. Is there anything I'm doing wrong or anything that I can do to improve their speed aside from improving the network? Just found this awesome post with some good performance recommendations. Any other comments?

Thanks much.


Answer:

Why do spring/hibernate read-only database transactions run slower than read-write?

Ok this has been an interesting ride. Lot for me to learn and share. Some of the below should have been obvious but hopefully my ignorance and what I've learned will be helpful to others.

<tldr> The short answer to question #1 was that hibernate starts off a @Transaction(readOnly = true) session with a set session.transaction.read.only synchronous JDBC call and ends with a set session.transaction.read.write call. These calls are not sent when doing read-write calls which is why read-only calls were slower. </tldr>

The longer answer to question #2 involves the following details of the steps that I took to try and reduce our remote database performance:

  1. First thing that we did was switch our database VPN from TCP to UDP after reading this OpenVPN optimization page. Sigh. I should have known about this. I also added the following settings to the OpenVPN client and server configs. Read-only transaction overhead dropped from 480ms to 141ms but was still more than read-write's 100ms. Big win.

    ; Got these from: https://community.openvpn.net/openvpn/wiki/Gigabit_Networks_Linux
    proto udp
    tun-mtu 6000
    fragment 0
    mssfix 0
    
  2. In looking closely at the tcpdump output (tcpdump ... -X for the win), I noticed that there were a lot of unnecessary auto-commit and read-only/read-write JDBC calls being made. Upgrading to a newer version of the awesome HikariCP connection pool library we use helped with this. In version 2.4.1 they added some intelligence which reduced some of these calls. Read-only transaction overhead down to 120ms. Read-write still at 100ms. Nice.

  3. Brett Wooldridge, the author of HikariCP pointed me to MySQL driver settings that might help. Thanks much dude. Adding the following settings to our MySQL JDBC URL tells the driver to use the software state of the connection and not ask the server for the status.

    jdbc:mysql://.../database?useLocalSessionState=true&useLocalTransactionState=true
    

    These settings caused more of the synchronous JDBC commands to be removed. Read-only transaction overhead dropped to 60ms and now is the same as read-write. Woo hoo.

    Edit/WARNING: we actually rolled back adding useLocalTransactionState=true after bugs were found where the driver was not sending transaction information.

  4. But in looking more at the tcpdump output, I still saw read-only/read-write transaction settings being sent. My last fix was to write a custom read-only detecting pool that gives out connections from a special pool if it sees the first call to the connection is connection.setReadOnly(true).

    Using this custom pool dropped the transaction overhead for both read-only and read-write connections to 20ms. I think it basically removed the last of the JDBC transaction overhead calls. Here's the source of the two classes that I wrote from my home page write up of all this. The code is relatively brittle and relies on Hibernate doing a connection.setReadOnly(true) first thing but it seems to be working well and I documented it in the XML and code carefully.

So basic @Transaction overhead went from 480ms to 20ms over a couple days of work. 100 "real life" hibernate calls to a dao.find(...) method started at 55 seconds and ended at 4.5 seconds. Pretty kick ass. Wish it was always this easy to get a 10x speed improvement.

Hope my experience helps others.

Question:

In my Spring Boot project I have implemented following service method:

@Transactional
public boolean validateBoard(Board board) {
    boolean result = false;
    if (inProgress(board)) {
        if (!canPlayWithCurrentBoard(board)) {
            update(board, new Date(), Board.AFK);
            throw new InvalidStateException(ErrorMessage.BOARD_TIMEOUT_REACHED);
        }
        if (!canSelectCards(board)) {
            update(board, new Date(), Board.COMPLETED);
            throw new InvalidStateException(ErrorMessage.ALL_BOARD_CARDS_ALREADY_SELECTED);
        }
        result = true;
    }
    return result;
}

inside of this method I use another service method which is called update:

@Transactional(propagation = Propagation.REQUIRES_NEW)
public Board update(Board board, Date finishedDate, Integer status) {
    board.setStatus(status);
    board.setFinishedDate(finishedDate);

    return boardRepository.save(board);
}

I need to commit changes to database in update method independently of the owner transaction which is started in validateBoard method. Right now any changes is rolling back in case of any exception.

Even with @Transactional(propagation = Propagation.REQUIRES_NEW) it doesn't work.

How to correctly do this with Spring and allow nested transactions ?


Answer:

This documentation covers your problem - https://docs.spring.io/spring-framework/docs/current/spring-framework-reference/data-access.html#transaction-declarative-annotations

In proxy mode (which is the default), only external method calls coming in through the proxy are intercepted. This means that self-invocation, in effect, a method within the target object calling another method of the target object, will not lead to an actual transaction at runtime even if the invoked method is marked with @Transactional. Also, the proxy must be fully initialized to provide the expected behaviour so you should not rely on this feature in your initialization code, i.e. @PostConstruct.

However, there is an option to switch to AspectJ mode

Question:

I previously had a post on this issue that was resolved. However since rebuilding the project with auto wired beans and less XML configuration I find I am revisiting this issue. I have followed the way my previous project implemented this but it doesn't work. Can someone help me with why or what I should change to make it work?

I am on purpose using a non existent table name in the insert user details method to deliberately throw an exception. However the statements for insert user and insert user roles are not rolled back. Please help.


My current design for the registration is like this.

Part of servlet.xml:

<context:component-scan base-package="com.doyleisgod.golfer.controllers"/>
<context:component-scan base-package="com.doyleisgod.golfer.dao"/>
<context:component-scan base-package="com.doyleisgod.golfer.services"/>
<context:component-scan base-package="com.doyleisgod.golfer.validators"/>

Part of application context:

<context:annotation-config />
<tx:annotation-driven />    

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="driverClassName" value="${jdbc.driverClassName}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</bean>

<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource"/>
</bean>

Registration controller:

package com.doyleisgod.golfer.controllers;

import javax.validation.Valid;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.InitBinder;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import com.doyleisgod.golfer.formdata.RegistrationForm;
import com.doyleisgod.golfer.services.IRegistrationService;
import com.doyleisgod.golfer.validators.RegistrationFormValidator;

/**
 * Description: Registration controller provides and processes the registration form.
 * @author Chris Doyle
*/
@Controller
@RequestMapping("/registration.htm")
public class RegistrationController {
    protected final Log logger = LogFactory.getLog(getClass());
    @Autowired private IRegistrationService iRegistrationService;
    @Autowired private RegistrationFormValidator registrationFormValidator;

    // sets a customer validator for the registration form
    @InitBinder
    protected void initBinder(WebDataBinder binder) {
        binder.setValidator(registrationFormValidator);
    }

    // Description: Method called by a get request to the registration controller. Returns the
    @RequestMapping(method=RequestMethod.GET)
    public String registration (Model model){
        model.addAttribute(new RegistrationForm());
        return "registration";
    }

     // Description: Method called by a post request to the registration controller. Method calls validation on the registration form using custom validator and returning 
     // any errors back to the user. 
    @RequestMapping(method=RequestMethod.POST)
    public String processRegistration (@Valid RegistrationForm registrationForm, BindingResult bindingResult, Model model){
        logger.info("Received the following registration form details");
        logger.info(registrationForm.toString());

        if (bindingResult.hasErrors()) {
            logger.warn("Registration Validation Failed");
            model.addAttribute("validationError", "Please correct the fields marked with errors");
            return "registration";
        }

        try {
            iRegistrationService.registerUser(registrationForm);
        } catch (Exception e) {
            logger.error("An Exception has occured processing the registration form");
            model.addAttribute("exceptionError", "An exception has occured, please try again.");
            e.printStackTrace();
            return "registration";
        }

        return "redirect:login.htm?registration=sucessful";
    }
}

Registration service:

package com.doyleisgod.golfer.services;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.authentication.encoding.ShaPasswordEncoder;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.transaction.support.TransactionSynchronizationManager;

import com.doyleisgod.golfer.dao.IRegistrationDAO;
import com.doyleisgod.golfer.formdata.RegistrationForm;

@Service("IRegistrationService")
public class RegistrationService implements IRegistrationService {
    @Autowired private IRegistrationDAO iRegistrationDAO;
    private final boolean enabled = true;
    private final String roles = "ROLE_USER";


    @Override
    @Transactional (rollbackFor = Exception.class)
    public void registerUser(RegistrationForm registrationForm) throws Exception {
        System.out.println("inside the registerUser method. is wrapped in transaction: "+TransactionSynchronizationManager.isActualTransactionActive());

        String username = registrationForm.getUsername();
        String password = registrationForm.getPassword();
        String firstname = registrationForm.getFirstname();
        String lastname = registrationForm.getLastname();
        String email = registrationForm.getEmail();
        int handicap = Integer.parseInt(registrationForm.getHandicap());
        String encryptedPassword = ((new ShaPasswordEncoder()).encodePassword(password, username));

        iRegistrationDAO.insertUser(username, encryptedPassword, enabled);
        iRegistrationDAO.insertRoles(username, roles);
        iRegistrationDAO.insertUserDetails(username, firstname, lastname, email, handicap);
    }

    @Override
    public boolean checkUser(String username) {
        return iRegistrationDAO.checkUserName(username);
    }
}

Registration DAO:

package com.doyleisgod.golfer.dao;

import javax.annotation.Resource;
import org.apache.commons.dbcp.BasicDataSource;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.support.TransactionSynchronizationManager;

@Repository("iRegistrationDAO")
public class RegistrationDAO extends JdbcTemplate implements IRegistrationDAO {

    @Resource private BasicDataSource dataSource;

    @Override
    public boolean checkUserName(String username) {
        int db_user = queryForInt("select count(username) from users where username = ?", username);

        if (db_user == 1 ){
            return true;
        }

        return false;
    }

    @Override
    public void insertUser(String username, String password, boolean enabled) throws Exception {
        System.out.println("inside the insertuser method. is wrapped in transaction: "+TransactionSynchronizationManager.isActualTransactionActive());

        update("insert into users (username, password, enabled) VALUES (?,?,?)", username, password, enabled);
    }

    @Override
    public void insertRoles(String username, String roles) throws Exception {
        update("insert into user_roles (username, authority) VALUES (?,?)", username, roles);
    }

    @Override
    public void insertUserDetails(String username, String firstname, String lastname, String email, int handicap) throws Exception {
        update("insert into user_detailss (username, first_name, last_name, email_address, handicap)" + 
                "VALUES (?,?,?,?,?)", username, firstname, lastname, email, handicap);

    }

    public void setDataSource(BasicDataSource dataSource) {
        this.dataSource = dataSource;
    }

    public BasicDataSource getDataSource() {
        return dataSource;
    }
}

Answer:

The reason that moving the context:component-scan tags to the application context xml fixed the transactional behavior is: <tx:annotation-driven /> is a post-processor that wraps @Transactional annotated bean methods with an AOP method interceptor which handles transactional behavior. Spring post-processors, only operate on the specific application context they are defined in.

In your case, you have defined the <tx:annotation-driven /> post-processor in the application context, while the beans annotated with @Transactional are in the servlet application context. Thus, the <tx:annotation-driven /> post-processor only operated on the application context beans, not the servlet context beans. When the context:component-scan tags were moved to the application context, then the <tx:annotation-driven /> post-processor wrapped their transactional methods appropriately.

Hope that makes some sense.

[Edit]

What is the difference between the Application Context and a Servlet Context?

What is a Spring post-processor and how does it work?

What is AOP in Spring?

Question:

1 quick question on Spring JPA repositories transactionality. I have a service that is not marked as transactional and calls Spring JPA repository method

userRegistrationRepository.deleteByEmail(email);

And it is defined as

@Repository
public interface UserRegistrationRepository extends JpaRepository<UserRegistration, Long> {

    UserRegistration findByEmail(String email);

    void deleteByEmail(String email);

}

The problem is that it fails with "No EntityManager with actual transaction available for current thread - cannot reliably process 'remove' call; nested exception is javax.persistence.TransactionRequiredException" exception.

Ok, I can solve it by marking the service or deleteByEmail(..) method as transactional, but I just can't understand why it crashes now. Spring documentation explicitly states that "CRUD methods on repository instances are transactional by default." (http://docs.spring.io/spring-data/jpa/docs/current/reference/html/#transactions), but apparently this one is not... So Is this statement related to only members of CrudRepository?

ps: that's for Spring Data JPA 1.9.4


Answer:

You are right. Only CRUD methods (CrudRepository methods) are by default marked as transactional. If you are using custom query methods you should explicitly mark it with @Transactional annotation.

@Repository
public interface UserRegistrationRepository extends JpaRepository<UserRegistration, Long> {

    UserRegistration findByEmail(String email);

    @Transactional
    void deleteByEmail(String email);

}

You should also be aware about consequences of marking repository interface methods instead of service methods. If you are using default transaction propagation configuration (Propagation.REQUIRED) then:

The transaction configuration at the repositories will be neglected then as the outer transaction configuration determines the actual one used.

http://docs.spring.io/spring-data/jpa/docs/current/reference/html/#transactions

If you want more information about how it is implemented, take a look at default CrudRepository / JpaRepository implementation - SimpleJpaRepository (which you are probably using):

https://github.com/spring-projects/spring-data-jpa/blob/master/src/main/java/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java

The interesting lines are here:

@Transactional(readOnly = true)
public class SimpleJpaRepository<T, ID> implements JpaRepositoryImplementation<T, ID> {

and some of transactional methods here:

@Transactional
public void deleteById(ID id) {
@Transactional
public <S extends T> S save(S entity) {

Question:

I have a Spring 3.2 application that uses Hibernate 4 and Spring Transactions. All the methods were working great and I could access correctly the database to save or retrieve entities. Then, I introduced some multithreading, and since each thread was accessing to db I was getting the following error from Hibernate:

org.hibernate.HibernateException: Illegal attempt to associate a collection with two open sessions

I read from the web that I've to add <prop key="hibernate.current_session_context_class">thread</prop> to my Hibernate configuration, but now every time I try to access the db I get:

org.hibernate.HibernateException: saveOrUpdate is not valid without active transaction

However my service methods are annotated with @Transactional, and all was working fine before the add of <prop key="hibernate.current_session_context_class">thread</prop>.

Why there is no transaction although the methods are annotated with @Transactional? How can I solve this problem?

Here is my Hibernate configuration (including the session context property):

<?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:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
    http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd">

<!-- Hibernate session factory -->
<bean
    id="sessionFactory"
    class="org.springframework.orm.hibernate4.LocalSessionFactoryBean" >
    <property name="dataSource" >
        <ref bean="dataSource" />
    </property>
    <property name="hibernateProperties" >
        <props>
            <prop key="hibernate.hbm2ddl.auto">create</prop> 
            <prop key="hibernate.dialect" >org.hibernate.dialect.MySQLDialect</prop>
            <prop key="hibernate.show_sql">true</prop>
            <prop key="hibernate.current_session_context_class">thread</prop>  
        </props>
    </property>   
    <property name="annotatedClasses" >
        <list>
            ...
        </list>
    </property> 
</bean>

<bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
    <property name="sessionFactory" ref="sessionFactory"/>
</bean>

<tx:annotation-driven transaction-manager="transactionManager"/>


Answer:

When using spring and spring managed transactions never mess around with the hibernate.current_session_context_class property UNLESS you are using JTA.

Spring will by default set its own CurrentSessionContext implementation (the SpringSessionContext), however if you set it yourself this will not be the case. Basically breaking proper transaction integration.

The only reason for changing this setting is whenever you want to use JTA managed transactions, then you have to setup this to properly integrate with JTA.