Re: StackOverflowError under serialization leaves pagemap locked

2010-03-19 Thread Nigel Parker
Thanks for all your help, Johan and Igor. Problem solved we think. One
of the pages was holding a reference to the session. With multiple
Ajax requests on the same page the session size was doubling each
time, eventually giving stack overflow.

Nigel


Or:

http://wicketstuff.org/maven/repository/org/apache/wicket/wicket/1.4-SNAPSHOT/

That should also have the latest fix

- Original message -

the fix is in 1.4.x branch and will be part of 1.4.8.

in the meantime you can build a fresh snapshot yourself and drop that
into your application

http://svn.apache.org/repos/asf/wicket/branches/wicket-1.4.x

-igor

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Re: StackOverflowError under serialization leaves pagemap locked

2010-03-19 Thread Nigel Parker
OK, WICKET-2789 added.

Thanks again

Nigel

---

we can modify serializable checker to check if anything is holding a
reference to session or application and catch the error right away. please
add a jira issue for this.

-igor


Re: StackOverflowError under serialization leaves pagemap locked

2010-03-18 Thread Nigel Parker

Thank you Johan for your reply. Agree that original problem should be fixed.
This is a critical problem for us. We have found out during the last 24
hours that some of our pages are retaining a session reference. With Ajax
requests this gives a doubling of session size for every request, and we now
believe this to be the cause of the StackOverflowErrors. We will try this in
production tomorrow.

We upgraded to to 1.4.7 but still see that the pagemap is locked when the
stack overflows. Do you know if the fix to WICKET-2075 is in 1.4.7?

Thanks
Nigel


Johan Compagner wrote:
 
 i fixed 2075 so that it should always unlock the pages.
 
 Problem is that you still could get weird errors because that page is not
 in
 a valid state in the session.
 So if back buttons/page versions are used it could be that that doesnt
 work
 
 So what should be fixed is the original problem
 
 
 
 On Wed, Mar 17, 2010 at 21:03, Nigel Parker nigel.par...@mazeppa.no
 wrote:
 
 We are a Wicket shop and for one of our clients have been running a
 Wicket application successfully for over 2 years. We are now at
 version 1.4.0. The traffic on the system is increasing and we are now
 seeing an increased frequency of pagemap locking which is beginning to
 be a serious problem for the users. By subclassing WebRequestCycle we
 have identified that a StackOverflowError under serialization in
 RequestCycle.detach() leaves the pagemap locked for the next minute.
 If our analysis is correct this is essentially the problem reported as
 https://issues.apache.org/jira/browse/WICKET-2075. Unfortunately we
 cannot reproduce the problem in our test environment and it occurs
 only in about one in every thousand requests with no apparent
 consistent pattern about what the user has been doing. Can anybody
 suggest an immediate strategy for further investigations? In
 particular:

 - is there a practical way to find out what is causing the
 serialization problem. The stack trace is no help. We do in many cases
 have large amounts of data in the session, but doubling the default
 stack size leaves the problem frequency unchanged leading us to
 suspect a logical error rather the sheer amount of data.

 - by overriding RequestCycle.detach() and catching the
 StackOverflowError we can get control when the error occurs. Is there
 any way we can persuade Wicket to release the pagemap lock? I have
 looked at the code and this doesn't look straightforward.

 - can we get Wicket itself to suppress the StackOverflowError so that
 detach() continues and releases the lock?

 Grateful for any suggestions.

 Nigel

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StackOverflowError under serialization leaves pagemap locked

2010-03-17 Thread Nigel Parker
We are a Wicket shop and for one of our clients have been running a
Wicket application successfully for over 2 years. We are now at
version 1.4.0. The traffic on the system is increasing and we are now
seeing an increased frequency of pagemap locking which is beginning to
be a serious problem for the users. By subclassing WebRequestCycle we
have identified that a StackOverflowError under serialization in
RequestCycle.detach() leaves the pagemap locked for the next minute.
If our analysis is correct this is essentially the problem reported as
https://issues.apache.org/jira/browse/WICKET-2075. Unfortunately we
cannot reproduce the problem in our test environment and it occurs
only in about one in every thousand requests with no apparent
consistent pattern about what the user has been doing. Can anybody
suggest an immediate strategy for further investigations? In
particular:

- is there a practical way to find out what is causing the
serialization problem. The stack trace is no help. We do in many cases
have large amounts of data in the session, but doubling the default
stack size leaves the problem frequency unchanged leading us to
suspect a logical error rather the sheer amount of data.

- by overriding RequestCycle.detach() and catching the
StackOverflowError we can get control when the error occurs. Is there
any way we can persuade Wicket to release the pagemap lock? I have
looked at the code and this doesn't look straightforward.

- can we get Wicket itself to suppress the StackOverflowError so that
detach() continues and releases the lock?

Grateful for any suggestions.

Nigel

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