[jira] [Resolved] (WICKET-6908) Possible bug / edge case where page is not detached

["Sven Meier (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/WICKET-6908?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

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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