[jira] [Commented] (TAP5-2499) Race condition in EntityManagerSource#getEntityManagerFactory

["ASF subversion and git services (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TAP5-2499?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15194258#comment-15194258 ] 

ASF subversion and git services commented on TAP5-2499:
-------------------------------------------------------

Commit 940bd2a51df3a96c14da7d1a861f387820b65efe in tapestry-5's branch refs/heads/master from kaosko
[ https://git-wip-us.apache.org/repos/asf?p=tapestry-5.git;h=940bd2a ]

FIXED - TAP5-2499: Race condition in
EntityManagerSource#getEntityManagerFactory 

- if EntityManagerFactory is not found, synchronize on the service
itself, double check the existence of the emf and create and put a new
emf in the map


> Race condition in EntityManagerSource#getEntityManagerFactory
> -------------------------------------------------------------
>
>                 Key: TAP5-2499
>                 URL: https://issues.apache.org/jira/browse/TAP5-2499
>             Project: Tapestry 5
>          Issue Type: Bug
>          Components: tapestry-jpa
>    Affects Versions: 5.4, 5.3.8
>            Reporter: Dmitry Gusev
>            Assignee: Kalle Korhonen
>
> On application start if more than one thread needs an entity manager more than one instance of EntityManagerFactory may be created.
> This is undesirable, because EMF may use a connection pool and creating more than one instance will lead to too many open database connections.
> EntityManagerSourceImpl.java:
> {code}
>     public EntityManagerFactory getEntityManagerFactory(final String persistenceUnitName)
>     {
>         EntityManagerFactory emf = entityManagerFactories.get(persistenceUnitName);
>         if (emf == null)
>         {
>             emf = createEntityManagerFactory(persistenceUnitName);
>             entityManagerFactories.put(persistenceUnitName, emf);
>         }
>         return emf;
>     }
> {code}
> Above code needs some synchronization.



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