Question

This is my code (it’s JAX-RS + JPA):

@Path("/")
public class Foo {
  private static final EntityManagerFactory FACTORY = 
    Persistence.createEntityManagerFactory("foo");
  @POST
  public void save(String name) {
    EntityManager em = this.FACTORY.createEntityManager();
    EntityTransaction trans = em.getTransaction();
    trans.begin();
    MyEntity entity = new MyEntity();
    em.persist(entity);
    em.flush();
    trans.commit();
    em.close();
  }
}

I’m using OpenJPA 1.2.2. Connections to MySQL are never got closed and in some time I see “too many connections”. What is wrong with this design?

Answer 1

What happens in your code in the event of errors? Are you guaranteed to reach the em.close() line? Are you seeing occasional exceptions, perhaps caught elsewhere?

Put your tidy-up code in finally blocks so that they are guaranteed to be run.

See this link for an explanation.