Welcome to the Hibernate Second Level Cache Example Tutorial. Today we will look into Hibernate EHCache that is the most popular Hibernate Second Level Cache provider.
One of the major benefit of using Hibernate in large application is it’s support for cache, hence reducing database queries and better performance. In earlier example, we looked into the Hibernate First Level Cache and today we will look into Hibernate Second Level Cache using Hibernate EHCache implementation. Hibernate Second Level cache providers include EHCache and Infinispan, but EHCache is more popular and we will use it for our example project. However before we move to our project, we should know different strategies for caching an object.
Since EHCache supports all the above cache strategies, it’s the best choice when you are looking for second level cache in hibernate. I would not go into much detail about EHCache, my main focus will be to get it working for hibernate application. Create a maven project in the Eclipse or your favorite IDE, final implementation will look like below image. Let’s look into each component of the application one by one.
For hibernate second level cache, we would need to add ehcache-core and hibernate-ehcache dependencies in our application. EHCache uses slf4j for logging, so I have also added slf4j-simple for logging purposes. I am using the latest versions of all these APIs, there is a slight chance that hibernate-ehcache APIs are not compatible with the ehcache-core API, in that case you need to check the pom.xml of hibernate-ehcache to find out the correct version to use. Our final pom.xml looks like below.
<project xmlns="https://maven.apache.org/POM/4.0.0" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="https://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.journaldev.hibernate</groupId>
<artifactId>HibernateEHCacheExample</artifactId>
<version>0.0.1-SNAPSHOT</version>
<description>Hibernate Secondary Level Cache Example using EHCache implementation</description>
<dependencies>
<!-- Hibernate Core API -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>4.3.5.Final</version>
</dependency>
<!-- MySQL Driver -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.0.5</version>
</dependency>
<!-- EHCache Core APIs -->
<dependency>
<groupId>net.sf.ehcache</groupId>
<artifactId>ehcache-core</artifactId>
<version>2.6.9</version>
</dependency>
<!-- Hibernate EHCache API -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-ehcache</artifactId>
<version>4.3.5.Final</version>
</dependency>
<!-- EHCache uses slf4j for logging -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.7.5</version>
</dependency>
</dependencies>
</project>
Hibernate Second level cache is disabled by default, so we would need to enable it and add some configurations to get it working. Our hibernate.cfg.xml file looks like below.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration SYSTEM "classpath://org/hibernate/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.password">pankaj123</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost/TestDB</property>
<property name="hibernate.connection.username">pankaj</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.current_session_context_class">thread</property>
<property name="hibernate.show_sql">true</property>
<property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property>
<!-- For singleton factory -->
<!-- <property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory</property>
-->
<!-- enable second level cache and query cache -->
<property name="hibernate.cache.use_second_level_cache">true</property>
<property name="hibernate.cache.use_query_cache">true</property>
<property name="net.sf.ehcache.configurationResourceName">/myehcache.xml</property>
<mapping class="com.journaldev.hibernate.model.Employee" />
<mapping class="com.journaldev.hibernate.model.Address" />
</session-factory>
</hibernate-configuration>
Some important points about hibernate second level cache configurations are:
org.hibernate.cache.ehcache.EhCacheRegionFactory
for this. If you want the factory class to be singleton, you should use org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory
class. If you are using Hibernate 3, corresponding classes will be net.sf.ehcache.hibernate.EhCacheRegionFactory
and net.sf.ehcache.hibernate.SingletonEhCacheRegionFactory
.Our EHCache configuration file myehcache.xml looks like below.
<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="ehcache.xsd" updateCheck="true"
monitoring="autodetect" dynamicConfig="true">
<diskStore path="java.io.tmpdir/ehcache" />
<defaultCache maxEntriesLocalHeap="10000" eternal="false"
timeToIdleSeconds="120" timeToLiveSeconds="120" diskSpoolBufferSizeMB="30"
maxEntriesLocalDisk="10000000" diskExpiryThreadIntervalSeconds="120"
memoryStoreEvictionPolicy="LRU" statistics="true">
<persistence strategy="localTempSwap" />
</defaultCache>
<cache name="employee" maxEntriesLocalHeap="10000" eternal="false"
timeToIdleSeconds="5" timeToLiveSeconds="10">
<persistence strategy="localTempSwap" />
</cache>
<cache name="org.hibernate.cache.internal.StandardQueryCache"
maxEntriesLocalHeap="5" eternal="false" timeToLiveSeconds="120">
<persistence strategy="localTempSwap" />
</cache>
<cache name="org.hibernate.cache.spi.UpdateTimestampsCache"
maxEntriesLocalHeap="5000" eternal="true">
<persistence strategy="localTempSwap" />
</cache>
</ehcache>
Hibernate EHCache provides a lot of options, I won’t go into much detail but some of the important configurations above are:
org.hibernate.cache.internal.StandardQueryCache
and org.hibernate.cache.spi.UpdateTimestampsCache
are defined because EHCache was giving warning to that.We use org.hibernate.annotations.Cache
annotation to provide the caching configuration. org.hibernate.annotations.CacheConcurrencyStrategy
is used to define the caching strategy and we can also define the cache region to use for the model beans.
package com.journaldev.hibernate.model;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.Table;
import org.hibernate.annotations.Cache;
import org.hibernate.annotations.CacheConcurrencyStrategy;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Parameter;
@Entity
@Table(name = "ADDRESS")
@Cache(usage=CacheConcurrencyStrategy.READ_ONLY, region="employee")
public class Address {
@Id
@Column(name = "emp_id", unique = true, nullable = false)
@GeneratedValue(generator = "gen")
@GenericGenerator(name = "gen", strategy = "foreign",
parameters = { @Parameter(name = "property", value = "employee") })
private long id;
@Column(name = "address_line1")
private String addressLine1;
@Column(name = "zipcode")
private String zipcode;
@Column(name = "city")
private String city;
@OneToOne
@PrimaryKeyJoinColumn
private Employee employee;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getAddressLine1() {
return addressLine1;
}
public void setAddressLine1(String addressLine1) {
this.addressLine1 = addressLine1;
}
public String getZipcode() {
return zipcode;
}
public void setZipcode(String zipcode) {
this.zipcode = zipcode;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public Employee getEmployee() {
return employee;
}
public void setEmployee(Employee employee) {
this.employee = employee;
}
}
package com.journaldev.hibernate.model;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.Table;
import org.hibernate.annotations.Cache;
import org.hibernate.annotations.CacheConcurrencyStrategy;
import org.hibernate.annotations.Cascade;
@Entity
@Table(name = "EMPLOYEE")
@Cache(usage=CacheConcurrencyStrategy.READ_ONLY, region="employee")
public class Employee {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "emp_id")
private long id;
@Column(name = "emp_name")
private String name;
@Column(name = "emp_salary")
private double salary;
@OneToOne(mappedBy = "employee")
@Cascade(value = org.hibernate.annotations.CascadeType.ALL)
private Address address;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public double getSalary() {
return salary;
}
public void setSalary(double salary) {
this.salary = salary;
}
}
Note that I am using the same database setup as in HQL example, you might want to check that to create the database tables and load sample data.
We have a simple utility class to configure hibernate and get the SessionFactory
singleton instance.
package com.journaldev.hibernate.util;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
public class HibernateUtil {
private static SessionFactory sessionFactory;
private static SessionFactory buildSessionFactory() {
try {
// Create the SessionFactory from hibernate.cfg.xml
Configuration configuration = new Configuration();
configuration.configure("hibernate.cfg.xml");
System.out.println("Hibernate Configuration loaded");
ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
System.out.println("Hibernate serviceRegistry created");
SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
return sessionFactory;
}
catch (Throwable ex) {
System.err.println("Initial SessionFactory creation failed." + ex);
ex.printStackTrace();
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
if(sessionFactory == null) sessionFactory = buildSessionFactory();
return sessionFactory;
}
}
Our hibernate second level cache project using Hibernate EHCache is ready, let’s write a simple program to test it.
package com.journaldev.hibernate.main;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.stat.Statistics;
import com.journaldev.hibernate.model.Employee;
import com.journaldev.hibernate.util.HibernateUtil;
public class HibernateEHCacheMain {
public static void main(String[] args) {
System.out.println("Temp Dir:"+System.getProperty("java.io.tmpdir"));
//Initialize Sessions
SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
Statistics stats = sessionFactory.getStatistics();
System.out.println("Stats enabled="+stats.isStatisticsEnabled());
stats.setStatisticsEnabled(true);
System.out.println("Stats enabled="+stats.isStatisticsEnabled());
Session session = sessionFactory.openSession();
Session otherSession = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Transaction otherTransaction = otherSession.beginTransaction();
printStats(stats, 0);
Employee emp = (Employee) session.load(Employee.class, 1L);
printData(emp, stats, 1);
emp = (Employee) session.load(Employee.class, 1L);
printData(emp, stats, 2);
//clear first level cache, so that second level cache is used
session.evict(emp);
emp = (Employee) session.load(Employee.class, 1L);
printData(emp, stats, 3);
emp = (Employee) session.load(Employee.class, 3L);
printData(emp, stats, 4);
emp = (Employee) otherSession.load(Employee.class, 1L);
printData(emp, stats, 5);
//Release resources
transaction.commit();
otherTransaction.commit();
sessionFactory.close();
}
private static void printStats(Statistics stats, int i) {
System.out.println("***** " + i + " *****");
System.out.println("Fetch Count="
+ stats.getEntityFetchCount());
System.out.println("Second Level Hit Count="
+ stats.getSecondLevelCacheHitCount());
System.out
.println("Second Level Miss Count="
+ stats
.getSecondLevelCacheMissCount());
System.out.println("Second Level Put Count="
+ stats.getSecondLevelCachePutCount());
}
private static void printData(Employee emp, Statistics stats, int count) {
System.out.println(count+":: Name="+emp.getName()+", Zipcode="+emp.getAddress().getZipcode());
printStats(stats, count);
}
}
org.hibernate.stat.Statistics
provides the statistics of Hibernate SessionFactory, we are using it to print the fetch count and second level cache hit, miss and put count. Statistics are disabled by default for better performance, that’s why I am enabling it at the start of the program. When we run above program, we get a lot of output generated by Hibernate and EHCache APIs, but we are interested in the data that we are printing. A sample run prints following output.
Temp Dir:/var/folders/h4/q73jjy0902g51wkw0w69c0600000gn/T/
Hibernate Configuration loaded
Hibernate serviceRegistry created
Stats enabled=false
Stats enabled=true
***** 0 *****
Fetch Count=0
Second Level Hit Count=0
Second Level Miss Count=0
Second Level Put Count=0
Hibernate: select employee0_.emp_id as emp_id1_1_0_, employee0_.emp_name as emp_name2_1_0_, employee0_.emp_salary as emp_sala3_1_0_, address1_.emp_id as emp_id1_0_1_, address1_.address_line1 as address_2_0_1_, address1_.city as city3_0_1_, address1_.zipcode as zipcode4_0_1_ from EMPLOYEE employee0_ left outer join ADDRESS address1_ on employee0_.emp_id=address1_.emp_id where employee0_.emp_id=?
1:: Name=Pankaj, Zipcode=95129
***** 1 *****
Fetch Count=1
Second Level Hit Count=0
Second Level Miss Count=1
Second Level Put Count=2
2:: Name=Pankaj, Zipcode=95129
***** 2 *****
Fetch Count=1
Second Level Hit Count=0
Second Level Miss Count=1
Second Level Put Count=2
3:: Name=Pankaj, Zipcode=95129
***** 3 *****
Fetch Count=1
Second Level Hit Count=2
Second Level Miss Count=1
Second Level Put Count=2
Hibernate: select employee0_.emp_id as emp_id1_1_0_, employee0_.emp_name as emp_name2_1_0_, employee0_.emp_salary as emp_sala3_1_0_, address1_.emp_id as emp_id1_0_1_, address1_.address_line1 as address_2_0_1_, address1_.city as city3_0_1_, address1_.zipcode as zipcode4_0_1_ from EMPLOYEE employee0_ left outer join ADDRESS address1_ on employee0_.emp_id=address1_.emp_id where employee0_.emp_id=?
4:: Name=Lisa, Zipcode=560100
***** 4 *****
Fetch Count=2
Second Level Hit Count=2
Second Level Miss Count=2
Second Level Put Count=4
5:: Name=Pankaj, Zipcode=95129
***** 5 *****
Fetch Count=2
Second Level Hit Count=4
Second Level Miss Count=2
Second Level Put Count=4
As you can see from output, statistics were disabled at first but we enabled it for checking our hibernate second level cache. Step by step explanation of the output is as follows:
evict()
method to remove the employee object from the first level cache, now when we are trying to load it, hibernate finds it in the second level cache. That’s why no database query is fired and fetch count remains 1. Notice that hit count goes from 0 to 2 because both Employee and Address objects are read from the second level cache. Second level miss and put count remains at the earlier value.So it’s clear that our Hibernate second level cache; Hibernate EHCache; is working fine. Hibernate statistics are helpful in finding the bottleneck in the system and optimize it to reduce the fetch count and load more data from the cache. That’s all for the Hibernate EHCache example, I hope it will help you in configuring EHCache in your hibernate applications and getting better performance through hibernate second level cache. You can download the sample project from below link and use other stats data to learn more.
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Hello Pankaj, I have a EJB based project where the hibernate-ehcache and hibernate-core version are 5.3.14.Final. Here all the entity classes are defined inside persistance.xml file . For example :- org.hibernate.ejb.HibernatePersistence ${datasource.jta.RateManager-core} true ENABLE_SELECTIVE CALLBACK net.atos.wlp.commoncomponent.rates.internal.Rate net.atos.wlp.commoncomponent.rates.internal.CurrencyPair I have made the class net.atos.wlp.commoncomponent.rates.internal.Rate cacheable. My rate-hibernate.cfg.xml has the following settings. true org.hibernate.cache.ehcache.EhCacheRegionFactory ehcache.xml In my ehcache.xml file i have following user defined entry along with default cache… But when i start my application inside Jboss 7.3 I found from the log I found below warning message HHH90001006: Missing cache[<>#RateManager-core.rate] was created on-the-fly. The created cache will use a provider-specific default configuration: make sure you defined one. As a result of which hibernate 2nd level cache is still working but it is not using my user defined cache rather it is reading the default cache setting present in the ehcache.xml. Any idea how hibernate 2nd level cache will work according to my user defined settings rather than default cache setting present in ehv\cache.xml file. Thanks Annada Lenka
- ANNADA LENKA
Thanks for detailed explanation, have few doubts. 1. Why you have started a transaction when there are only read operation in your code? 2. Why did you close the session factory? Is it just to clear the cached data?
- Kuldeep
Thanks Pankaj ,it’s very helpful.
- ShuhaoWen
Thank you Pankaj for sharing your knowlegde!
- Sergio
Thanks, pankaj good explanation. Keep posting. Thanks once again.
- anp
you should set the value of timeToLiveSeconds a littler bigger.
- Ning
this is very helpful
- Arun SIngh
too good. Worked for me. Great explanation.
- Shashank
i am using criteria query or HQL to retrieve a list of values and i am not using query level cache.will second level cache work for it as each time i am trying its hitting the database
- nithin
Hi, When I am executing this project I am getting the following error: Initial SessionFactory creation failed.java.lang.NoSuchMethodError: javax.persistence.OneToOne.orphanRemoval()Z java.lang.NoSuchMethodError: javax.persistence.OneToOne.orphanRemoval()Z at org.hibernate.cfg.AnnotationBinder.processElementAnnotations(AnnotationBinder.java:1836) at org.hibernate.cfg.AnnotationBinder.processIdPropertiesIfNotAlready(AnnotationBinder.java:963) at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:796) at org.hibernate.cfg.Configuration$MetadataSourceQueue.processAnnotatedClassesQueue(Configuration.java:3788) at org.hibernate.cfg.Configuration$MetadataSourceQueue.processMetadata(Configuration.java:3742) at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1410) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1844) at com.journaldev.hibernate.util.HibernateUtil.buildSessionFactory(HibernateUtil.java:22) at com.journaldev.hibernate.util.HibernateUtil.getSessionFactory(HibernateUtil.java:34) at com.journaldev.hibernate.main.HibernateEHCacheMain.main(HibernateEHCacheMain.java:18) Exception in thread “main” java.lang.ExceptionInInitializerError at com.journaldev.hibernate.util.HibernateUtil.buildSessionFactory(HibernateUtil.java:29) at com.journaldev.hibernate.util.HibernateUtil.getSessionFactory(HibernateUtil.java:34) at com.journaldev.hibernate.main.HibernateEHCacheMain.main(HibernateEHCacheMain.java:18) Caused by: java.lang.NoSuchMethodError: javax.persistence.OneToOne.orphanRemoval()Z at org.hibernate.cfg.AnnotationBinder.processElementAnnotations(AnnotationBinder.java:1836) at org.hibernate.cfg.AnnotationBinder.processIdPropertiesIfNotAlready(AnnotationBinder.java:963) at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:796) at org.hibernate.cfg.Configuration$MetadataSourceQueue.processAnnotatedClassesQueue(Configuration.java:3788) at org.hibernate.cfg.Configuration$MetadataSourceQueue.processMetadata(Configuration.java:3742) at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1410) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1844) at com.journaldev.hibernate.util.HibernateUtil.buildSessionFactory(HibernateUtil.java:22) … 2 more
- Ajay