Do I have to close() every EntityManager?

I have just started migrating my homegrown persistence framework to JPA.

Given that the persistence frameworks hide a lot of the plumbing, I'm interested in knowing if NOT closing EntityManagers will create a resource leak, or if the frameworks will collect and close them for me.

I intend in all places to close them, but do I HAVE to?

At the moment using TopLink, just because it works with NetBeans easily, but am happy to investigate other JPA providers.

Asked by: Freddie836 | Posted: 21-01-2022

Answer 1

It depends how you obtained it.

If you created it using EntityManagerFactory you will have to close it no matter what framework you use.

If you obtained it using dependency injection (eg using EJB and @PersistenceContext annotation) you should not close it by hand (AFAIK it will cause RuntimeException).

Answered by: Sienna387 | Posted: 22-02-2022

Answer 2

You should.

Frameworks have no idea how you intend to use the EM, so they cannot close it (except, may be, on finalization, which is not guaranteed). Yes, not closing them would create a resource leak.

The idea is the same as "always close java.sql.Connection" (despite some data sources have settings to close them automatically by inactivity) or "always close Hibernate session".

Besides, if you plan to write portable code, you shouldn't rely on specific JPA provider "being smart" -- other may fail to close the EM in time.

Answered by: Sawyer484 | Posted: 22-02-2022

Answer 3

I have obtained EntityManager using @PersistenceContext annotation in my repository. I can see that after the connectionpools reaches its maxPoolSize it does not get cleaned up.

However if I create EntityManager using EntityManagerFactory and call entitymanager.close() then connections are getting cleaned up. I am using c3p0 as connectionpool library.

Answered by: Rafael996 | Posted: 22-02-2022

Answer 4

Justo to give my 5 cents you must remember to close your EntityManagerFactory. I was just using it to create my EntityManager and it opened and kept opend a new conection pool every time.

Answered by: Fenton753 | Posted: 22-02-2022

Similar questions

java - With a DAO pattern, do you ever expose the EntityManager or Session as a parameter?

Is there ever a case in a standard webapp where one would pass an EntityManager or Session as a parameter to a DAO call, i.e. findPersonByName(String name, Session session)? Or should the the opening and closing of the session be abstracted in the implementation?

java - Does Hibernate EntityManager include Core?

I'm using Hibernate's implementation of JPA. My Maven pom.xml references hibernate-entitymanager. My question is, does Hibernate EntityManager (called "Standard Java Persistence API for Java SE and Java EE" on Hibernate's home page) depend on or use the Hibernate Core code? I've discovered a bug ...

java - Entitymanager causing memory leak?

I have a slow memory leak in my Java application. I was wondering if this could be caused by not always closing the Entitymanager when used. However using myeclipse to generate DB code, I'm getting methods like this: public Meit update(Meit entity) {"updating Meit instance"); try { Meit result = getEntityManager().merge(entity);"update successful"); ...

java - how do i pass EntityManager to @PostUpdate

I want to save history of changes, so in @PostUpdate i want to create new instance of another entity and save it, how do i pass EntityManager to that method?

java - JPA EntityManager deletes all records in database

I have one Servlet that does insertion into my database. This is working fine. A second Servlet displays what the first one has inserted, however whenever I run the displaying Servlet, all records in all my tables are being deleted! My JPA implementation is EclipseLink and the db is MySQL. Is it possible that the way I retrieve a EntityManagerFactory is triggering a recreation of the db schema? Enti...

java - sync entitymanager from database

i have a swing desktop application that use a entitymanagerfactory, but when this application is executed many times at the same time, the diferents entity managers have old data that was modified by others and this changes will not visible until the next entitymanagerfactory... how can i sync in anytime the entitymanager with the database data??

java - JSF + Spring + JPA + Hibernate: keep entitymanager alive when rendering view?

Totally new to Spring & Java development but working on a project for a class with some experienced developers. I believe we're using Spring MVC as our web layer(but I'm a C# guy so I may be mistaken in that regard). We have a view that gets an object with lazily loaded properties -- pretty straightforward stuff. Yet when I call one of these properties within a JSF view, I get this error: failed to ...

java - Hibernate EntityManager Factory - EHCache

I am having more problems with getting the entity manager factory up and running. Unfortunately, the error message is very vague. I'm not quite sure why it's not more descriptive, but it is what it is: Hibernate Startup log messages (trace level), no entities configured for brevity (same error message either way except all the startup messages creating this relationship or that ...): 2010-02-12 20...

java - Glassfish JPA: Problems injecting EntityManager

I am new to Java EE. I tried to get some first examples running (JPA). I am using Glassfish v3. The trouble is that I don't get the App Server injecting the EntityManager. Hear is one example which I extended with a JSP client. Entity...

java - Problem on jboss lookup entitymanager

I have my ear-project deployed in jboss 5.1GA. From webapp i don't have problem, the lookup of my ejb3 work fine! es: ShoppingCart sc= (ShoppingCart) (new InitialContext()).lookup("idelivery-ear-1.0/ShoppingCartBean/remote"); also the iniection of my EntityManager work fine! @PersistenceContext private EntityManager manager; From test env...

Still can't find your answer? Check out these amazing Java communities for help...

Java Reddit Community | Java Help Reddit Community | Java Community | Java Discord | Java Programmers (Facebook) | Java developers (Facebook)