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https://issues.apache.org/jira/browse/WICKET-6908?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sven Meier resolved WICKET-6908.
--------------------------------
Resolution: Fixed
All handlers are now properly detached again.
> Possible bug / edge case where page is not detached
> ---------------------------------------------------
>
> Key: WICKET-6908
> URL: https://issues.apache.org/jira/browse/WICKET-6908
> Project: Wicket
> Issue Type: Bug
> Components: wicket-core
> Affects Versions: 9.4.0, 8.13.0
> Reporter: Sebastian Gooren
> Assignee: Sven Meier
> Priority: Minor
> Fix For: 10.0.0, 9.5.0, 8.14
>
> Attachments: quickstart.zip
>
>
> Today I spent the better part of my day investigating a bug report regarding
> a hibernate LazyInitializationException.
> Since we use detaching models everywhere and (in general) never see such
> issues anymore, this one was interesting :-)
>
> After much debugging I found out what is happening.
>
> We have a page which has a database model + links for prev/next item (in the
> database).
> When the users double-clicks on one of the links, the first click is OK, and
> the second click throws a StalePageException during request cycle processing.
>
> So far, normal.
>
> However, stepping through the wicket code, this is what happens:
>
> 1) Resolve to ListenerRequestHandler, execute it, throws StalePageException
> 2) exception mapper handles this and we execute a RenderPageRequestHandler,
> which re-renders the page
> 3) the request cycle detaches, which delegates in part to
> RequestHandlerExecutor.detach()
> 4) The handlers to detach are both handlers from step 1 and 2; During the
> detach of ListenerRequestHandler, it initializes ListenerLogData, which (in
> the PageLogData ctor) throws the StalePageException again!
> 5) The second handler (RenderPageRequestHandler) is not detached, thus all
> models in the page are not detached
> 6) The user clicks on a link and boom, the models are all still attached and
> there we get the LazyInitializationException
>
> I think that (a) RequestHandlerExecutor.detach() should ensure all handlers
> are detached, and (b) that failing to collect LogData should not stop the
> detaching of a request handler.
>
> What do you think?
>
> I tried to make the simplest possible Quickstart to demonstrate this.
>
> Weird stuff: on the homepage of the quick start, the page is properly
> detached when a stale link is clicked;
> On another (test) page, the page is not properly detached.
>
> Steps to reproduce:
>
> Run Quickstart
> Click on “Test” link on homepage
> Observe that the following is logged:
>
> Model still attached? false
> Page detaching
>
> Now click on "Click me (stale link)!”
> Now refresh the page (re-render)
>
> Observe that the following is logged:
>
> Model still attached? true
> Page detaching
>
> —> So the page was not detached
>
> These steps don’t have the same result on the homepage. So my guess is there
> is some relation to the fact that we are interacting with a stateful,
> non-mounted page.
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