I am trying to write a method that bulk adds entities to the database. Here's my method:
#Transactional
protected void bulkInsert(List<?> entities) {
int batchSize = 25;
AtomicInteger i = new AtomicInteger(0);
try {
em.getTransaction().begin();
entities.parallelStream().forEach(e -> {
em.persist(e);
if ( i.get() > 0 && i.get() % batchSize == 0 ) {
em.flush();
em.clear();
}
i.incrementAndGet();
});
em.getTransaction().commit();
} catch (RuntimeException e) {
LOG.error("Error", e);
} finally {
if (em != null) {
em.close();
}
}
}
But when I run this I get the following error:
java.lang.IllegalStateException: Not allowed to create transaction on shared EntityManager - use Spring transactions or EJB CMT instead
at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:248) ~[spring-orm-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at com.sun.proxy.$Proxy145.getTransaction(Unknown Source) ~[na:na]
I tried removing the #Transactional annotation and still the same error. I tried using Session by doing Session session = em.unwrap(Session.class); but that still resulted in an error (although different error)
How do I bulk insert objects?
in pure hibernate exists managed- and non-managed environments
Non-managed environment
If an JPA persistence layer runs in a non-managed environment, database >connections are usually handled by Hibernate's pooling mechanism behind the >scenes. The common entity manager and transaction handling idiom looks like > this:
// Non-managed environment idiom
EntityManager em = emf.createEntityManager(); EntityTransaction tx =
null; try {
tx = em.getTransaction();
tx.begin();
// do some work
...
tx.commit(); } catch (RuntimeException e) {
if ( tx != null && tx.isActive() ) tx.rollback();
throw e; // or display error message } finally {
em.close(); }
Using JTA
If you use bean-managed transactions (BMT), the code will
look like this:
// BMT idiom
#Resource public UserTransaction utx;
#Resource public
EntityManagerFactory factory;
public void doBusiness() {
EntityManager em = factory.createEntityManager();
try {
// do some work
...
utx.commit(); } catch (RuntimeException e) {
if (utx != null) utx.rollback();
throw e; // or display error message
} finally {
em.close();
}
With Container Managed Transactions (CMT) in an EJB3 container, transaction >demarcation is done in session bean annotations
or deployment descriptors, not programatically. The EntityManager will
automatically be flushed on transaction completion (and if you have
injected or lookup the EntityManager, it will be also closed
automatically). If an exception occurs during the EntityManager use,
transaction rollback occurs automatically if you don't catch the
exception. Since EntityManager exceptions are RuntimeExceptions they
will rollback the transaction as per the EJB specification (system
exception vs. application exception).
you should follow on of two princeple.
annotation #Transactional it's spring annotaniot not hibernate. if you didn;t configued it (or you did configured spring) doen't work.
PC
An EntityManager is an inexpensive, non-threadsafe object that should
be used once, for a single business process
call em.flush() ,em.clear() might be dangerous .
Related
I need to create an Entity Manager manually to support having multiple datasources. I've realised that by creating it manually (instead of autowiring it as when you have only one single datasource), I actually do need to set all the JPA properties manually too, including what are usually set with default values by Spring. This means all the JPA parameters I specified in application.yaml and what Spring normally set default values for have now to be loaded and set manually.
Is there anyway to create an Entity Manager manually but have it automatically use all the JPA properties in application.yaml?
Here's my code
public LocalContainerEntityManagerFactoryBean entityManager(EntityManagerFactoryBuilder builder, DataSource secondDataSource) {
Map<String, Object> props = new HashMap<>();
// Is there a way to not do this one by one for all of the default JPA properties and what I specified in application.yaml?
props.put("hibernate.physical_naming_strategy", "org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy");
// props.put("prop1", "propvalue1");
// ...
return builder.dataSource(secondDataSource).packages(MyEntity.class).properties(props).build();
}
Let's say, you have a persistence-unit with the name myData
private EntityManager getEntityManager() {
EntityManagerFactory emf = null;
try {
emf = Persistence.createEntityManagerFactory("myData");
} catch (Exception e) {
log.warn("An Error has occurred while creating persistence layer", e);
}
if (emf != null) {
return emf.createEntityManager();
} else {
log.warn("An error has occurred while retrieving Entity Manager from Persistence factory");
return null;
}
}
And use like below
final EntityManager em = getEntityManager();
assert em != null;
EntityTransaction entityTransaction = em.getTransaction();
try {
entityTransaction.begin();
userList.stream().forEach(user -> {
em.merge(RestUtil.convertToDBUser(user));
});
entityTransaction.commit();
log.info("Completed data persistence ");
} catch (RuntimeException e) {
if (entityTransaction.isActive()) {
entityTransaction.rollback();
}
log.warn("An error has occurred while committing JDBC transaction. ", e);
throw e;
} finally {
em.close();
}
I'm new to Hibernate. I've created the SessionFactory and obtaining the Session like below. And I'm using c3p0 connection provider
public static SessionFactory getSessionFactory() {
try {
if (sessionFactory == null) {
Configuration configuration = loadDBConfiguration();
if (configuration != null) {
sessionFactory = configuration.buildSessionFactory();
} else {
log.info("---- Configuration failed ----");
}
}
} catch (Exception ex) {
log.info("---- Initial SessionFactory creation failed ----");
}
return sessionFactory;
}
public static EntityManagerFactory getEntityManagerFactory() {
try {
Session session = getSessionFactory().openSession();
entityManagerFactory = session.getEntityManagerFactory();
} catch (Exception e) {
log.error(e);
}
return entityManagerFactory;
}
public static EntityManager getEntityManager() {
try {
EntityManagerFactory entityManagerFactory = getEntityManagerFactory();
return entityManagerFactory.createEntityManager();
} catch (Exception e) {
log.error(e);
}
return null;
}
And i'm confused with below things.
Should i close the connection after commit(), or c3p0 connection provider will close after commit().
Shall i call getEntityManager() on each request or should i use like singleton
If i'm used as singleton, then does it affect any parallel transaction.begin() or transaction.commit() if server receives multiple request at same time.
Also in singleton the entity still persist in session until it gets closed or clear manually. So what i need to do in this case.
Currently the getEntityManager() gets called in all my EntityManager Classes like UserManager, AccountsManager. After some period of time in RDS it shows like 20connections, even my application not handling any user requests.
You should close your connections. Since your connections are wrapped by the database connection pool, they will not get physically closed, but they will return to the pool. This needs to be done otherwise the connection pool will think the connections are being used and when you hit the pool limit, no new connections will be open.
Keep the session factory as a singleton. You should open a new session for each thread.
I have buit a Webservice using these technologies + c3p0 for database handling. It works ok most of the time but I have a 3-5% ratio (sometimes even a 10%) of failed acces due to this error.
I am using Hibernate this way:
-Session Factory
private static SessionFactory buildSessionFactory() {
try {
Configuration configuration = new Configuration();
configuration.configure();
serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
// Create the SessionFactory from hibernate.cfg.xml
return configuration
.buildSessionFactory(serviceRegistry);
} catch (Throwable ex) {
System.err.println("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
//reabrimos la sesion si esta cerrada al liberar los recursos
if(sessionFactory.isClosed())
{
System.out.println("Reopen session");
sessionFactory.openSession();
}
return sessionFactory;
}
Then in my hibernate.cfg.xml I have the following line:
<property name="current_session_context_class">thread</property>
Finally in my endpoints I have defined a hibernate_session class which I use as follows:
#Path("/projects")
public class ProjectServiceImpl {
#Context
SecurityContext security;
Session hibernate_session = null;
#POST
#Path("sync.json")
#Produces(value = {"application/json",
"application/vnd.myapp-v1+json",
"application/vnd.myapp-v2+json"})
public Response syncProjects(
#DefaultValue("") #FormParam("projects") String in_projects_str,
#DefaultValue("0") #FormParam("last_sync") long last_sync,
#Context Request request) {
//...
hibernate_session = HibernateUtil.getSessionFactory()
.getCurrentSession();
if (hibernate_session == null) {
ResponseMessage rm = new ResponseMessage();
rm.setCode(Status.INTERNAL_SERVER_ERROR.getStatusCode());
rm.setMessage("Hibernate Session is Null");
rm.setType("ERROR");
return Response.status(Status.INTERNAL_SERVER_ERROR).entity(rm)
.type("application/json").build();
}
try {
hibernate_session.beginTransaction();
//Database work...
hibernate_session.flush();
hibernate_session.getTransaction().commit();
}catch (RuntimeException | IllegalAccessException
| InvocationTargetException e) {
try {
if (hibernate_session.getTransaction() != null) {
hibernate_session.getTransaction().rollback();
}
} catch (RuntimeException rbe) {
System.err.println("Couldn’t roll back transaction");
}
e.printStackTrace();
ResponseMessage rm = new ResponseMessage();
rm.setCode(Status.INTERNAL_SERVER_ERROR.getStatusCode());
rm.setMessage(e.getMessage());
rm.setType("ERROR");
return Response.status(Status.INTERNAL_SERVER_ERROR).entity(rm)
.type("application/json").build();
}
}
return Response.ok().entity(result_entity)
.type("application/json").build();
}
My hibernate_session is a class attribute, do I have to change it to a local variable?. As far as I know the end points will be executed in different threads so I have assumed that I am working with different instances of my endpoint container class and these class attributes will not get overriden by multiple request.
Any light you can shed on this topic will be appreciated,
Thanks in advance
Thanks all for your replies. I finally managed to solve the problem.
In one of my multiple entries there was a begin transaction (necessary to create criterias) but was not commited. The result was that a reused thread that had called that method before would throw a nested exception. By commiting the transaction the problem was solved :)
You aren't using openSession and getCurrentSession properly.
public static SessionFactory getSessionFactory() {
//reabrimos la sesion si esta cerrada al liberar los recursos
//change this: if(sessionFactory.isClosed()) to this:
if(sessionFactory == null || sessionFactory.isClosed())
{
System.out.println("Reopen session"); // Really setup session factory
//change this: sessionFactory.openSession(); to this:
sessionFactory = buildSessionFactory();
}
return sessionFactory;
}
That's not the problem though, your code there just isn't doing what it's supposed to. You need to change:
hibernate_session = HibernateUtil.getSessionFactory().getCurrentSession();
to
hibernate_session = HibernateUtil.getSessionFactory().openSession();
As per the SessionFactory Javadoc:
Obtains the current session. The definition of what exactly "current" means controlled by the CurrentSessionContext impl configured for use.
It's safe to assume your CurrentSessionContext is not thread safe.
It seems that a transaction is started, and before the transaction gets commited an attempt to start a new transaction is made.
This explains the error message that says that a nested transaction (the second transaction inside the ongoing transaction) is not supported.
This could be caused for example by incorrect error handling, for example starting a transaction, not catching an exception or catch and ignore and then try to begin a second transaction without having done either commit or rollback.
An idiom similar to this one should be used when doing programmatic transaction mananagement:
try {
sess.getTransaction().begin();
// do some work
sess.getTransaction().commit()
}
catch (RuntimeException e) {
sess.getTransaction().rollback();
throw e;
}
Also important to bear mind is that after a rollback the session cannot be reused, as it's in an inconsistent state.
If using a framework like Spring, the use of the annotation #Transactional for declarative transaction management solves most of these problems for us and leads to more maintainable code, EJB3 has also similar functionality.
I m using glassfish v2 and persistence in a web application.
I m calling persistence codes using a normal java class file inside a web Application
I can select easily using this code: -
#PersistenceUnit
public EntityManagerFactory emf;
EntityManager em;
public List fname (String id) {
String fname = null;
List persons = null;
//private PersistenceManagerFactory persistenceManagerFactory;
try {
emf = Persistence.createEntityManagerFactory("WebApplicationSecurityPU");
em = emf.createEntityManager();
persons = em.createQuery("select r from Roleuser r").getResultList();
int i=0;
for (i=0;i<persons.size(); i++)
System.out.println("Testing n "+ i +" " + persons.get(i));
} catch(Exception e) {
System.out.println("" + e);
}
finally {
if(em != null) {
em.close();
}
}
return persons;
}
I want to update using JTA as the persistence.xml file has
transaction-type="JTA"
When i try using update using this code i get a nullPointerException without any traces in the log
#PersistenceUnit
public EntityManagerFactory emf;
EntityManager em;
Context context;
#Resource
private UserTransaction utx;
public List fname (String id) {
String fname = null;
List persons = null;
try {
emf = Persistence.createEntityManagerFactory("WebApplicationSecurityPU");
utx.begin();
em = emf.createEntityManager();
int m = em.createQuery("update Roleuser r set r.firstName = 'Jignesh I' where r.userID=9").executeUpdate();
utx.commit();
} catch(Exception e) {
System.out.println("" + e);
}
finally {
if(em != null) {
em.close();
}
}
return persons;
}
Any help
Thanks
Pradyut
Perhaps your bean isn't managed - i.e. it's not part of any context (spring, EJB). How are you creating your object?
You really should not call createEntityManager() - inject one using #PersistenceContext
You must be absolutely sure you need JTA before using it.
You seem to be using PersistenceUnit, but then re-assign the etm - I'd suggest drop both and see p2 above.
If you are not using any dependecy injection at all, then drop all the annotations, retain the current code, and type:
em.getTransaction().begin();
...
em.getTransaction().commit();
(and define RESOURCE_LOCAL in your persistence.xml. You really don't need JTA)
well the code should be without any nightmares...(atleast for me in glassfish)
with the persistence.xml having
<persistence-unit name="WebApplicationSecurityPU" transaction-type="RESOURCE_LOCAL">
the code
#PersistenceUnit
public EntityManagerFactory emf;
public EntityManager em;
public EntityManager getEm() {
emf = Persistence.createEntityManagerFactory("WebApplicationSecurityPU");
em = emf.createEntityManager();
return em;
}
public List fname (String id) {
String fname = null;
List persons = null;
try {
System.out.println("test");
em = this.getEm();
em.getTransaction().begin();
int m = em.createQuery("update Roleuser r set r.firstName = 'Jignesh H' where r.userID=9").executeUpdate();
em.getTransaction().commit();
} catch(Exception e) {
System.out.println("" + e);
}
finally {
if(em != null) {
em.close();
}
}
return persons;
}
Any improvements are welcome...(actually needed...)
(How to go about using #PersistenceContext)
Thanks
Pradyut
Your "normal" class is very likely not a managed component i.e. a class whose life cycle is managed by the container (like Servlets, Servlet Filters, JSP tag handlers, JSF Managed Beans, ...) and can't benefit from resource injection1.
So neither the UserTransaction nor the EntityManagerFactory are injected here, hence the NullPointerException.
Honestly, you should try to use a container managed EntityManager, this would make your code less messy. If you cannot get it injected, get it via a JNDI lookup. See the resource below.
1 Have a look at Web Tier to Go With Java EE 5: A Look at Resource Injection for a nice overview of what can be injected, and where.
Resources
How to use EntityManager API in web module
References
JPA 1.0 specification
Section 5.2 "Obtaining an Entity Manager"
Section 5.6 "Container-managed Persistence Contexts"
i am using the following approach to sole lazy initialization problem in hibernate.Pleas tell me whether it will work or not .
I have to implement my transcation in my persistance layer compulsary due to some reasons.
public class CourseDAO {
Session session = null;
public CourseDAO()
{
this.session = this.session = HibernateUtil.getSessionFactory().getCurrentSession();
}
public Course findByID(int cid){
Course crc = null;
Transaction tx = null;
try {
tx = session.beginTransaction();
Query q = session.createQuery("from Course as course where course.cid = "+cid+" ");
crc = (Course) q.uniqueResult();
//note that i am not commiting my transcation here.Because If i do that i will not be able to
//do lazy fetch
}
catch (HibernateException e)
{
e.printStackTrace();
tx.rollback();
throw new DataAccessLayerException(e);
}
finally
{
}
return crc;
}
}
and in the filter i am using the folling code
session = HibernateUtil.getSessionFactory().getCurrentSession();
if(session.isOpen())
HibernateUtil.getSessionFactory().getCurrentSession().getTransaction().commit();
IS this approach right??
Can it can have any problem
could you explain why do you need to have ur transactions in ur repositories? the problem there is that they are going to be so fine-grained, so you are not gonna get any advantage from the session caching
then you are opening the transaction there but closing it in your filter. what happens if you access multiple repositories in your service? Maybe i am not understanding what you mean but i think you need to re-think the reasons that force you to manage your transactions in your repositories
When do you create you CourseDAO? If it is a singleton bean or something else that lives longer than a page view, it will need to keep a SessionFactory and generate a new Session when it needs one rather than keeping a Session.