First level cache not working with JPA and Hibernate

Question

I an new to use hibernate caching (first level, 2nd level and query cache).

My project is configured using Spring MVC and JPA.

I am testing first level cache using JUnit test case below.

public class FirstLevelCacheTest
{
    private static final Logger logger = LoggerFactory.getLogger(FirstLevelCacheTest.class);

    @PersistenceContext
    private EntityManager       entityManager;

    @Test
    public void testFirstLevelCacheTest()
    {
        Long clientId = 1L;

        // fetch the client entity from database first time
        Client client1 = entityManager.find(Client.class, clientId);
        logger.debug("Client Name : {}", client1.getName());

        // fetch the client entity again
        client1 = entityManager.find(Client.class, clientId);
        logger.debug("Client Name : {}", client1.getName());
    }
}

And my entity class is defined as :

@Entity
@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL)
@Table(name = "client")
public class Client extends BaseModel
{
    // instance variable declaration

    // getter and setter methods for instance variables
}

This should execute native query once in case first level cache is by default enabled. But I am getting result below while executing this query:

Hibernate: select client0_.id as id0_0_, client0_.created as created0_0_, client0_.createdBy as createdBy0_0_, client0_.updated as updated0_0_, client0_.updatedBy as updatedBy0_0_, client0_.contactNo as contactNo0_0_, client0_.contactPerson as contactP7_0_0_, client0_.contactPersonEmail as contactP8_0_0_, client0_.contactPersonNo as contactP9_0_0_, client0_.email as email0_0_, client0_.name as name0_0_ from client client0_ where client0_.id=?
[main] DEBUG Client Name : Client1
Hibernate: select client0_.id as id0_0_, client0_.created as created0_0_, client0_.createdBy as createdBy0_0_, client0_.updated as updated0_0_, client0_.updatedBy as updatedBy0_0_, client0_.contactNo as contactNo0_0_, client0_.contactPerson as contactP7_0_0_, client0_.contactPersonEmail as contactP8_0_0_, client0_.contactPersonNo as contactP9_0_0_, client0_.email as email0_0_, client0_.name as name0_0_ from client client0_ where client0_.id=?
[main] DEBUG Client Name : Client1

Below is my persistence related configurations:

@Configuration
@EnableTransactionManagement
public class PersistanceConfig
{
    // injection

    private String[] PACKAGES_TO_SCAN = new String[] { "com.mypackage1", "com.mypackage2" };

    @Bean
    public DataSource dataSource()
    {
        // dataSource setting 'com.mysql.jdbc.Driver' as a jdbc driver
    }

    private Properties jpaProperties()
    {
        Properties properties = new Properties();

        properties.put(AvailableSettings.DIALECT, hibernateDialect);
        properties.put(AvailableSettings.SHOW_SQL, hibernateShowSql);

        // 2nd level cache
        properties.put("hibernate.cache.use_second_level_cache", true);
        properties.put("hibernate.cache.region.factory_class", "org.hibernate.cache.ehcache.EhCacheRegionFactory");

        return properties;
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory()
    {
        // entity manager settings using dataSource and jpaProperties
    }

    @Bean
    public JpaTransactionManager transactionManager()
    {
        // transaction manager settings using entityManagerFactory
    }
}

Can anybody help me to sort out an issue or anything I am doing wrong ?

Thanks in advance !

Can you provide the code pieces where your activated the cache ? You should have an @Cacheable on your Client class. — Alexandre FILLATRE, May 15 '14 at 05:33
Also look at this section of the oracle documentation : http://docs.oracle.com/javaee/6/tutorial/doc/gkjia.html — Alexandre FILLATRE, May 15 '14 at 05:34
@AlexandreFILLATRE please look at updates in question. And I think we don't required to annotate entity using '@Cacheable' because first level cache is by default on. — Ashvin Kanani, May 15 '14 at 08:47

Vlad Mihalcea · Accepted Answer · 2021-01-09T16:59:09.647

10

You need to annotate the test method with @Transactional or use the Spring TransactionTemplate.

Even if retrieving an entity doesn't require a transaction, grouping multiple calls inside one would clearly specify the Persistence Context boundaries (where it is meant to start and where it should end).

To replicate the 1st Level Cache you need the same Unit Of Work throughout your test method, and annotating the test with @Transactional would start a transaction (a Spring logical transaction that's bound to the current executing Persistence Context transaction which correlates to the actual physical database transaction).

When the test method ends the Transaction is usually roll-back so no changes will be propagated to any successive test, but within the currently executing test method you get to see your own changes, which is the Isolation property in ACID.

edited Jan 09 '21 at 16:59

answered May 15 '14 at 06:43

Vlad Mihalcea

142,745
71
566
911

1

The following is wrong: "JPA operations always require a running Transaction, not only for persist/merge operations.". Only operations that change something in DB need a transaction (e.g. a SELECT operation that does not pessimist-lock any rows does not need a transaction). Also it depends on the autocommit flag/status (default it is false), but that is a longer story (check [this answer](http://stackoverflow.com/questions/21672454/application-managed-jpa-when-is-transaction-needed)). – V G May 15 '14 at 07:55
I am agreed with @Andrei-i that '@Transactional' is only required when there is something to persist/merge. – Ashvin Kanani May 15 '14 at 08:55
@vhad-mihalcea: This is fine that '@Transactional' on test method is working fine. But what if I create getById(java.lang.Long) to respective DAO ? Should I annotate this method with '@Transactional' ? If yes, what if I need to call this method number of time from Service layer using for loop, etc. ? – Ashvin Kanani May 15 '14 at 09:02
2

I usually have my service layer setting the @Transactional boundaries, not the DAO layer. This is because a service can end up calling multiple DAOs which you want to be executed in the same Transaction. This also addresses your loop getById problem, since inside a transaction you get the same Hibernate Session, therefore the 1st level cache will always return the same object instance, no matter how many times you call session.get() or entityManager.find() – Vlad Mihalcea May 15 '14 at 09:09

V G · Answer 2 · 2014-05-15T12:55:30.077

I have tested you scenario in a simple command line application and could not reproduce the problem. Tested with Hibernate 4.0.1 and Hibernate 4.3. Basically I fetched the same entity twice outside a transaction and the second SQL query is not executed. IMPORTANT: I called EntityManager.find() one after another, without any other operations between them (like opening a transaction, case which will trigger another SQL select).

I recommend you the following: 1. Make sure that you look also in the logs of your DB server (to be sure that Hibernate does not log the queries, although it does not send them). 2. Upgrade Hibernate to a newer version.

Another note: as far as I know, there is no requirement that Hibernate uses such a Cache.

persistence.xml I've used:

<persistence version="2.0" xmlns="http://xmlns.jcp.org/xml/ns/persistence"  
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
        xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_0.xsd"> 

    <persistence-unit name="my-PU" transaction-type="RESOURCE_LOCAL">

                <!--<provider>org.hibernate.ejb.HibernatePersistence</provider>-->
                <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>

                <class>com.package.Entity</class>
                <exclude-unlisted-classes>false</exclude-unlisted-classes>
                <properties>
                        <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
                        <property name="hibernate.hbm2ddl.import_files" valu="sql/import-users.sql"/>
                        <property name="hibernate.show_sql" value="true"/>
                        <property name="hibernate.format_sql" value="false"/>
                </properties>
    </persistence-unit>
</persistence>

I am using latest release of Hibernate and i.e. '4.3.5.Final'. — Ashvin Kanani, May 15 '14 at 09:50
Could you post your `persistence.xml` (or the way how you configure Hibernate)? What DB & Driver are you using? — V G, May 15 '14 at 09:52
I have also tested it with 4.3.5.Final and the same result: only one query is sent to DB. — V G, May 15 '14 at 10:05
I am not using persistence.xml instead I did java based configuration. For more information check updates in question. I am using MySQL as a DB. — Ashvin Kanani, May 15 '14 at 11:58

score 0 · Answer 3 · answered Dec 23 '19 at 11:53

0

@Transactional is responsible to handle to get the session object from the sessionFactory and the entityManger object from the entityManagerFactory First Level cache happened at session level or entityManger level so @Tranaction annotation is very important here

answered Dec 23 '19 at 11:53

ayman.mostafa

451
6
5

Can you explain what information this gives that isn't in the accepted answer? – Dragonthoughts Dec 23 '19 at 12:13

First level cache not working with JPA and Hibernate

3 Answers3