[jbossseam-issues] [JBoss JIRA] Commented: (JBSEAM-3652) Major reentrancy problem with "Page Scope" components and injection/disinjection

[Denis Forveille (JIRA)]

    [ https://jira.jboss.org/jira/browse/JBSEAM-3652?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12438507#action_12438507 ] 

Denis Forveille commented on JBSEAM-3652:
-----------------------------------------

Thanks for the fix in BijectionInterceptor Dan
However, for case #2, this breaks the contract of the @Create annotation that should be called only once per component in its scope IMHO.
With or without @Synchronized, @Create is called many times  foir the same component/scope in that case. I think calls to @Create should be serialized too. In our case this causes majors inconsistencies (Even with @Synchronized)
If you want me to create a separate jira for that, please let me know

Also what do you mean by "Page-scoped components are now synchronized by default. "? Did You changed that for v2.1.1? we are about to add @Synchronized to all our page scope components, maybe we'll wait until v2.1.1 then..

> Major reentrancy problem with "Page Scope" components and injection/disinjection
> --------------------------------------------------------------------------------
>
>                 Key: JBSEAM-3652
>                 URL: https://jira.jboss.org/jira/browse/JBSEAM-3652
>             Project: Seam
>          Issue Type: Bug
>    Affects Versions: 2.0.2.SP1, 2.0.3.CR1, 2.1.0.GA
>         Environment: WebSphere v6.1.0.17 in POJO Mode 
>            Reporter: Denis Forveille
>            Assignee: Dan Allen
>            Priority: Blocker
>             Fix For: 2.1.1.CR1
>
>         Attachments: Test3652.java, Test3652Conv.java, testJBSEAM3652.xhtml, traces.txt
>
>
> This bug is very similar to the JBSEAM-3295 bug, but for "Page Scope" components this time
> Under stress, we have random NPE, "conversation expired" and other strange eroors from time to time in production
> This is due to a flaw in the "BijectionInterceptor" class and it is quite easy to reproduce
> On a facelets page, we have a datatable with a list of h:commadLink, teh first page of a classic "list entities/showDetail" scheme. The controleur that manages the list is in "Page Scope"
> When the user clics on one of the link, then quickly clic on another link, another one etc...  without waiting for the detail view to show up, we have two concurrent request addressed to the same Page Scope component (Verified by putting traces in the BijectionInterceptor class)
> In BijectionInterceptor, in that case, counter == 2 after line 77  meaning there is two concurrent thread running: the current thread + another one currently "using" the component
> The counter will be decrease for the first time on line 82,  then a second time on line 129 and so, disinjection will occur on line 134. This occurs while there is another thread "using" the component, causing random NPE and other errors!!!!
> In fact this will happen each time counter >1, ie there is more than one "concurrent" request on the same component
> This alleviate some questions:- 
> - is this normal that 2 (or more) concurrent request from the same user/conversation/page acces the same page scope component concurrently (I thought seam was taking care of this and was serializing such requests...
> - is this normal that on line 88, components are outjected, only when the last concurrent "user" of the component exits the interceptor and not when each request "eixts" the interceptor?

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