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From "Pinaki Poddar (JIRA)" <j...@apache.org>
Subject [jira] Commented: (OPENJPA-305) Dynamic configuration of EntityManagerFactory
Date Fri, 03 Aug 2007 00:43:52 GMT

    [ https://issues.apache.org/jira/browse/OPENJPA-305?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12517415
] 

Pinaki Poddar commented on OPENJPA-305:
---------------------------------------

Dynamic (i.e. while EntityManagerFactory is alive) change of Configuration will impact the
pooling of BrokerFactory (which is the core implementation of which EntityManagerFactory is
a facade).

The pool maintains a Map of poolKey to BrokerFactory. A poolKey is effectively the Configuration
expressed as a Property. So dynamically changing configuration properties must take into account
the integrity of this pool which is till now based on the assumption of constancy of Configuration.

Possibility of using IdentityHashMap and use the Configuration instance (not its Property
values) as key:
  This is most likely *not* going to work. The idea of freezing the config at the first place
(perhaps) originated because callers who supply new copies of Configuration (that are same
by value but not by identity) expect to get the same Factory. 

> Dynamic configuration of EntityManagerFactory
> ---------------------------------------------
>
>                 Key: OPENJPA-305
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-305
>             Project: OpenJPA
>          Issue Type: New Feature
>            Reporter: Pinaki Poddar
>
> OpenJPA configures EntityManagerFactory at creation time via an instance of Configuartion
object. Once EntityManagerFactory is created and a EntityManager is issued from it -- the
Configuration is frozen by design. That is no further changes to Configuration is allowed
as long as EntityManagerFactory lives.
> For certain configuration properties, it is desirable to change them during the lifetime
of a EntityManagerFactory.
> This issue is raised to initiate a discussion on such a feature, the possibility and
limitations of dynamic update and track the impact of such a change as frozen Configuration
is an important assumption.
>  

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