Thanks again.  I am still interested in page stores though.  I'm not saying
they are related to the expiration issue but I am curious how do they manage
themselves.  I haven't been able to find much info online.  Does each one
just store a potentially unlimited number of pages or is there some resource
management going on?


Matej Knopp-2 wrote:
> 
> Hi,
> 
> wicket holds the last accessed page in pagemap and certain number of
> previous pages in DiskPageStore (serialized on disk). The last
> accessed page should never be evicted from pagemap and even if it was,
> it would still be stored on disk.
> 
> -Matej
> 
> On Fri, Jan 23, 2009 at 12:19 AM, UPBrandon <bcr...@up.com> wrote:
>>
>> Thanks Matej and Igor.  We are using sticky sessions (I can even see the
>> JSESSIONID in requests) and since a session sticks to a certain
>> server/instance, there shouldn't be any need for replicating sessions
>> among
>> instances.  There are dozens and dozens of web apps here and losing
>> sessions
>> hasn't been an issue.  Would it make any difference if I said that
>> sometime
>> a user may get a "page expired" error only 30 seconds after the last page
>> request?  But this is a problem that only happens occasionally and
>> supposedly under high load.
>>
>> Either way, I would still be interested in knowing more about how
>> Wicket's
>> session store works.
>> - Under what circumstances are pages evicted from a page map?
>> - Is there a limit on how many pages can be stored in a single page map?
>> - Are there any "global" (per Wicket instance, not per map or session)
>> limits on how many pages are held onto?
>> - Under what circumstances are page maps destroyed?  Only when a window
>> or
>> tab is closed?
>> - Does Wicket ever destroy a session or does it let the container manage
>> all
>> that?
>>
>> I guess what all of those questions really get is this - is there ever a
>> point where Wicket starts running out of space and has to "clean house?" 
>> If
>> so, what is the process that it goes through?
>>
>> -Brandon
>>
>>
>> igor.vaynberg wrote:
>>>
>>> yep. it looks like the servlet container is losing the session. do you
>>> have sticky sessions? if not then you need to have http session
>>> replication happening.
>>>
>>> -igor
>>>
>>> On Thu, Jan 22, 2009 at 1:11 PM, Matej Knopp <matej.kn...@gmail.com>
>>> wrote:
>>>> Well, as far as I can tell, there is nothing special going on in
>>>> Wicket that might cause session expiration. Last visited page is
>>>> basically a normal session property.
>>>>
>>>> To me this seems more likely to be servlet container / load balancer
>>>> issue.
>>>>
>>>> -Matej
>>>>
>>>> On Thu, Jan 22, 2009 at 9:21 PM, UPBrandon <bcr...@up.com> wrote:
>>>>>
>>>>> The project I work on uses Wicket 1.3.4 and we are using the default
>>>>> session
>>>>> store (SecondLevelCacheSessionStore.)
>>>>>
>>>>> The app is clustered and runs on WebLogic 8 through Apache.  I'm not
>>>>> entirely sure how those two are setup but I don't believe there is any
>>>>> resource sharing between instances in a cluster.  Instead, when a
>>>>> session is
>>>>> started, a WebLogic instance is chosen and all future requests in that
>>>>> session are sent to that one instance.  Using that setup, there
>>>>> shouldn't be
>>>>> any issues with a user's request going to a machine that doesn't have
>>>>> their
>>>>> page map.
>>>>>
>>>>> The problem is happening during normal "forward" use.  The example
>>>>> that
>>>>> I
>>>>> was given was a user taking a few minutes to fill out some information
>>>>> and
>>>>> by the time they submit the form, their session appears to have timed
>>>>> out
>>>>> and they get a page expired error.  I hope that helps to clarify
>>>>> things
>>>>> a
>>>>> bit.
>>>>>
>>>>>
>>>>> Matej Knopp-2 wrote:
>>>>>>
>>>>>> couple of questions:
>>>>>>
>>>>>> -what wicket version are you using?
>>>>>> -are you using httpsessionstore or secondlevelcachesessionstore
>>>>>> (default)?
>>>>>> -what application server/container are you using?
>>>>>> -are you running the application in clustered environment? if yes,
>>>>>> what kind of load balancing do you have?
>>>>>> -do the expirations happen during normal operation or only when using
>>>>>> back button (or using application in multiple tabs)
>>>>>>
>>>>>> -Matej
>>>>>>
>>>>>> On Thu, Jan 22, 2009 at 7:47 PM, UPBrandon <bcr...@up.com> wrote:
>>>>>>>
>>>>>>> In some of our Wicket applications, as the number of users has
>>>>>>> started
>>>>>>> to
>>>>>>> ramp up, we seem to be experiencing a scalability issue.  Some users
>>>>>>> have
>>>>>>> had problems with pages expiring quickly.  This is second-hand
>>>>>>> information
>>>>>>> so I can't elaborate much but supposedly, during peak times, pages
>>>>>>> are
>>>>>>> expiring after just a few minutes of inactivity.  It would be nice
>>>>>>> to
>>>>>>> be
>>>>>>> able to set a minimum retention time but I don't seem to see an
>>>>>>> option
>>>>>>> like
>>>>>>> that.  I've found information about how Wicket stores pages and
>>>>>>> revisions
>>>>>>> (http://cwiki.apache.org/WICKET/page-maps.html) but I haven't been
>>>>>>> able
>>>>>>> to
>>>>>>> find much on how Wicket manages that data when things start "filling
>>>>>>> up."
>>>
>>>>>>> Are there any good explanations out there on the web?
>>>>>>>
>>>>>>> -Brandon
>>>
>>
>> --
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>> Sent from the Wicket - User mailing list archive at Nabble.com.
>>
>>
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