I'm using Mojarra 2.2.4 on GlassFish 4 with Java 7.
As I understand from BalusC's answer to How and when is a @ViewScoped bean destroyed in JSF?, @ViewScoped beans should be destroyed in three cases:
- Post-back with non-null outcome
- Session expiration
- Maximum number of logical views in session exceeded
My beans are being destroyed in the first two cases, but not when the maximum number of logical views is exceeded. I have verified that the beans do expire when the maximum is exceeded (I get a ViewExpiredException), but they are still not destroyed until the session itself expires.
For memory consumption reasons, I would like to have the beans destroyed in this third case, especially since they are not usable after expiration.
Questions
- Why are the beans not destroyed when they expire?
- Is this a bug or expected behavior?
- What would be a clean work-around to make sure the beans get destroyed?
- Update: OmniFaces ViewScoped annotation destroys beans as soon as they expire.
Minimal Example
Here is my bean:
@javax.inject.Named("sandboxController")
@javax.faces.view.ViewScoped
public class SandboxController implements Serializable {
private static final Logger log = Logger.getLogger(SandboxController.class.getName());
@PostConstruct
public void postConstruct() {
log.log(Level.INFO, "Constructing SandboxController");
}
@PreDestroy
public void preDestroy() {
log.log(Level.INFO, "Destroying SandboxController");
}
public String getData() {
return "abcdefg";
}
}
and my sandbox.xhtml:
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html">
<body>
<h:form>
<h:outputText value="#{sandboxController.data}"/>
</h:form>
</body>
</html>
and part of my web.xml:
<context-param>
<param-name>com.sun.faces.numberOfLogicalViews</param-name>
<param-value>3</param-value>
</context-param>
<context-param>
<param-name>com.sun.faces.numberOfViewsInSession</param-name>
<param-value>3</param-value>
</context-param>
If I refresh the sandbox.xhtml 50 times, I get 50 copies of INFO: Constructing SandboxController in the log. The beans are not destroyed, regardless of how many times I refresh. VisualVM confirms that the beans are still referenced by the UIViewRoot's ViewMap. In my full-size bean, which maintains a fair bit of state, I quickly get an OutOfMemoryException.
When I manually expire the session, I get 50 copies of INFO: Destroying SandboxController.
If I add a submit button to sandbox.xhtml and load it up in 4 different tabs, then try to submit the first one, I get a ViewExpiredException, as expected, but the bean is still not destroyed.
The behavior is the same if I instead use the javax.faces.bean.ManagedBean and javax.faces.view.ViewScoped annotations. However, the OmniFaces annotation org.omnifaces.cdi.ViewScoped works properly.
To clarify...
My @ViewScoped beans are being destroyed on session expiration, unlike problems described in related questions such as Linked ViewScoped beans lead to memory leaks
I am not asking why each bean is not destroyed immediately on subsequent refresh as questioned here: JSF 2.1 ViewScopedBean @PreDestroy method is not called. I want to know why it is that even when they expire, and are no longer useful, they are still not destroyed, and thus continue consuming memory.
I was able to find a clean work-around by using the OmniFaces @ViewScoped annotation (org.omnifaces.cdi.ViewScoped) instead of the standard @ViewScoped (javax.faces.view.ViewScoped).
The OmniFaces ViewScoped correctly destroys the beans as soon as they expire.
See here for more details: http://showcase.omnifaces.org/cdi/ViewScoped
来源：https://stackoverflow.com/questions/20930396/why-are-expired-viewscoped-beans-not-destroyed-until-the-session-expires