1:32 p.m.
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https://jira.jboss.org/jira/browse/JBSEAM-3652?page=com.atlassian.jira.pl...
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Denis Forveille updated JBSEAM-3652:
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Attachment: Test3652.java
Test3652Conv.java
testJBSEAM3652.xhtml
Shane, I created a simple test case that shows the problem and I think I hit another bug,
ie that the method annotated with "@Create" may be called many times for a page
scope component even if it should not (I guess)
I uploaded the traces produced by 4 tests cases:
For the 4 cases, I clicked 6 times quickly on the link. The results:
Case 1 : We have a call in the ".xhtml" file that triggers the creation of the
component before the user can click on the link and we don't use long running
conversation
-> This illustrates the bug mentionned before in BijectionInterceptor. The component in
conversation scope is shared between calls until BijectionInterceptore disinject it as
described in my initial post (ie becomes null for one of the thread), then another
instance of this component is automaticaly created.
-> Calls to the "testMethod" method are not serialized as confirmed by the
post of Dan
-> Q: Besides the NPE, should'nt we have 6 different instances of the conversation
scoped component there as we are not in a long running conversation??
Case 2: The component is created when the user clics on the link and we don't use
long running conversation
-> @Create is called 6 times (!!!!), creating 6 different instances of the conversation
scope component. Wow !!!
-> Calls to the "testMethod" method are not serialized as confirmed by the
post of Dan
Case 3: We have a call in the .xhtml that triggers the creation of the component and we
have a long running conversation started on @Create
-> Works as expected, I guess: @Create si called only once, and calls to the
"testMethod" method are serialized
Case 4: The component is created when the user clics on the link and and we have a long
running conversation started on @Create
-> Quite similar to test case 2
-> @Create is called 6 times (!!!!), creating 6 different instances of the conversation
scope component. Wow !!!
-> Calls to the "testMethod" method are not serialized, because I think the
@Create methiod created 6 instances of the conversation scope component
To summarise:
1) this shows clearly the bug in BijectioNinterceptor (case 1)
2) there is another bug where @Create can be called many time for the same page scope
component
3) IMHO, page scope component should almost always be annotated with @Synchronized to
solve some forms of "double clics".
Major reentrancy problem with "Page Scope" components and
injection/disinjection
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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: Shane Bryzak
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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