3:13 p.m.
[
https://issues.jboss.org/browse/CDI-139?page=com.atlassian.jira.plugin.sy...
]
Mark Struberg commented on CDI-139:
-----------------------------------
Just a short notice:
I think this should get added to the spec that way we discussed: automatically destroying
all @Dependent contextual instances created via the Instance<T>.get() method when
the containing bean will be destroyes.
This will of course have a few side effects where this might be too aggressive:
Consider the following code:
@RequestScoped
public class X {
private @Inject Instance<Y> yProvider;
private static Y y;
@PostConstruct
void doInit() {
if (y == null) y = yProvider.select().get();
}
}
In this case we would 'destroy' y (calling @PreDestroy) at the end of the Request,
even if the static y member is still valid.
The same might happen if you store y somewhere else via classic java setters...
Support for unmanaged instances
-------------------------------
Key: CDI-139
URL: https://issues.jboss.org/browse/CDI-139
Project: CDI Specification Issues
Issue Type: Feature Request
Components: Beans
Affects Versions: 1.0
Reporter: Joshua Davis
Fix For: 1.1 (Proposed)
Allow the creation of unmanaged instances. The CDI context will not keep track of these
instances and the application will be responsible for cleaning them up. This is a fairly
typical usage of other DI frameworks such as Guice and PicoContainer.
Currently, if an ApplicationScoped object injects an {{Instance<T>}} interface, CDI
will manage all instances returned by the {{get()}} method as dependents of the
application scoped object. Those instances will be kept in memory by the CDI
implementation and will only be GC'd when the application scoped object is destroyed
(at the end of the application). This may look like a memory leak to the user (see
WELD-920).
From P. Muir on WELD-920
{quote}
We can describe instances which are attached (as the CDI 1.0 spec requires) as
"managed" instances, and those which the user takes responsibility for cleaning
up themselves as "unmanaged" instances. In CDI 1.1 I would like to add support
for unmanaged instances (the impl will just hand these over and forget about them) and
also to allow the app to request an unmanaged instance is cleaned up. Please can someone
file a CDI issue for this?
Weld could certainly be more friendly and more proactively discard instances. Ideas:
1) Analyse the dependent instance graph, and if there are no @PreDestroy/@Disposer
callbacks on in the graph, do not store the dependent instance for cleanup (this would be
a good general optimization
(2) Add a config option to allow instances created from Instance to be held only as long
as the app holds a reference, and if the app doesn't hold a reference for it's
lifetime, then Weld would not do any cleanup (Weld would hold a weak ref).
{quote}
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