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From Fang Lin <Fang...@u.washington.edu>
Subject RE: ConcurrentModificationException
Date Thu, 08 Dec 2011 05:59:12 GMT
Hi Dan,

I removed the error handling logic from the WebPage and have the CustomExceptionListener handles
all the Exceptions.

  @Override
  public IRequestHandler onException(RequestCycle cycle, Exception e)
  {
    logErr (cycle, e);
    if (e instanceof InvalidSession) {
      return new SessionErrHandler();
    }

    if (e instanceof GetFailedException) {
      return new DbErrHandler();
    }

    if (e instanceof ParameterException) {
      return new ParamErrHandler();
    }

    if (e instanceof DisallowedUwnetidException) {
      return new AccessErrHandler();
    }

    if (e instanceof SslException) {
      return new SslErrHandler();
    }

    return new RuntimeErrHandler();
  }
Each of these handlers redirect to a static error page.

Now I get this error:

Can't instantiate page using constructor 'public myuw.page.Main(org.apache.wicket.request.mapper.parameter.PageParameters)'
and argument 'f=[d], tab=[1]'. Might be it doesn't exist, may be it is not visible (public).
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:196)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:97)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:47)
        at org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:107)
        at org.apache.wicket.request.handler.PageProvider.resolvePageInstance(PageProvider.java:264)
        at org.apache.wicket.request.handler.PageProvider.getPageInstance(PageProvider.java:165)
        at org.apache.wicket.request.handler.ListenerInterfaceRequestHandler.getPage(ListenerInterfaceRequestHandler.java:100)
        at org.apache.wicket.request.handler.ListenerInterfaceRequestHandler.respond(ListenerInterfaceRequestHandler.java:165)
        at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:750)
        at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
        at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:252)
        at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:209)
        at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:280)
        at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:162)
        at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:218)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
Caused by: java.lang.reflect.InvocationTargetException: null
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:173)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:97)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:47)
        at org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:107)
        at org.apache.wicket.request.handler.PageProvider.resolvePageInstance(PageProvider.java:264)
        at org.apache.wicket.request.handler.PageProvider.getPageInstance(PageProvider.java:165)
        at org.apache.wicket.request.handler.ListenerInterfaceRequestHandler.getPage(ListenerInterfaceRequestHandler.java:100)
        at org.apache.wicket.request.handler.ListenerInterfaceRequestHandler.respond(ListenerInterfaceRequestHandler.java:165)
        at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:750)
        at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
        at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:252)
        at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:209)
        at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:280)
        at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:162)
        at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:218)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
Caused by: edu.washington.cac.myuw.servlet.session.NoExistingSessionException: An existing
user but the HttpSession is null
        at edu.washington.cac.myuw.servlet.session.UwSession.<init>(Unknown Source)
        at myuw.sessiono.MyUWSession.<init>(Unknown Source)
        at myuw.sessiono.MyUWSession.<init>(Unknown Source)
        at myuw.session.MyuwSession.setMyUWSession(Unknown Source)
        at myuw.page.BasePage.setMyUWSession(Unknown Source)
        at myuw.page.Main.setMyUWSession(Unknown Source)
        at myuw.page.BasePage.setup(Unknown Source)
        at myuw.page.Main.<init>(Unknown Source)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:173)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:97)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:47)
        at org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:107)
        at org.apache.wicket.request.handler.PageProvider.resolvePageInstance(PageProvider.java:264)
        at org.apache.wicket.request.handler.PageProvider.getPageInstance(PageProvider.java:165)
        at org.apache.wicket.request.handler.ListenerInterfaceRequestHandler.getPage(ListenerInterfaceRequestHandler.java:100)
        at org.apache.wicket.request.handler.ListenerInterfaceRequestHandler.respond(ListenerInterfaceRequestHandler.java:165)
        at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:750)


-----Original Message-----
From: Fang Lin [mailto:Fanglin@u.washington.edu] 
Sent: Wednesday, December 07, 2011 5:17 PM
To: 'users@wicket.apache.org'
Subject: RE: ConcurrentModificationException

Yes, that sounds like a better way as the handling logic is the same. Thanks!

Here is the stack trace when a ConcurrentModificationException occurs:
ERROR 07 17:08:51.968 setup:  [m.p.BasePage] edu.washington.cac.myuw.servlet.session.NoExistingSessionException:
An existing user but the HttpSession is null
        at edu.washington.cac.myuw.servlet.session.UwSession.<init>(Unknown Source)
        at myuw.sessiono.MyUWSession.<init>(Unknown Source)
        at myuw.sessiono.MyUWSession.<init>(Unknown Source)
        at myuw.session.MyuwSession.setMyUWSession(Unknown Source)
        at myuw.page.BasePage.setMyUWSession(Unknown Source)
        at myuw.page.BasePage.setup(Unknown Source)
        at myuw.page.Main.<init>(Unknown Source)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:177)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:68)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:47)
        at org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:103)
        at org.apache.wicket.request.handler.PageProvider.resolvePageInstance(PageProvider.java:264)
        at org.apache.wicket.request.handler.PageProvider.getPageInstance(PageProvider.java:165)
        at org.apache.wicket.request.handler.ListenerInterfaceRequestHandler.getPage(ListenerInterfaceRequestHandler.java:100)
        at org.apache.wicket.request.handler.ListenerInterfaceRequestHandler.respond(ListenerInterfaceRequestHandler.java:165)

INFO 07 17:08:51.968 >>>Route to User login [m.SessionErrHandler]
ERROR 07 17:08:51.976 setup:  [m.p.BasePage] edu.washington.cac.myuw.servlet.session.NoExistingSessionException:
An existing user but the HttpSession is null
        at edu.washington.cac.myuw.servlet.session.UwSession.<init>(Unknown Source)
        at myuw.sessiono.MyUWSession.<init>(Unknown Source)
        at myuw.sessiono.MyUWSession.<init>(Unknown Source)
        at myuw.session.MyuwSession.setMyUWSession(Unknown Source)
        at myuw.page.BasePage.setMyUWSession(Unknown Source)
        at myuw.page.BasePage.setup(Unknown Source)
        at myuw.page.Main.<init>(Unknown Source)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:177)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:68)
        at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:47)
        at org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:103)
        at org.apache.wicket.request.handler.PageProvider.resolvePageInstance(PageProvider.java:264)
        at org.apache.wicket.request.handler.PageProvider.getPageInstance(PageProvider.java:165)
        at org.apache.wicket.request.handler.PageAndComponentProvider.getComponent(PageAndComponentProvider.java:144)
        at org.apache.wicket.request.handler.logger.ListenerInterfaceLogData.tryToGetComponentClass(ListenerInterfaceLogData.java:80)

INFO 07 17:08:51.976 >>>Route to User login [m.SessionErrHandler]


-----Original Message-----
From: Dan Retzlaff [mailto:dretzlaff@gmail.com] 
Sent: Wednesday, December 07, 2011 4:48 PM
To: users@wicket.apache.org
Subject: Re: ConcurrentModificationException

Gotcha. Well I'm still confused, but I do have a suggestion. Instead of
catching and handling exceptions like this in your page, let them propagate
out and handle them when Wicket calls your
RequestCycleListener#onException(). No point in finishing the page
construction/rendering, right?

On Wed, Dec 7, 2011 at 4:27 PM, Fang Lin <Fanglin@u.washington.edu> wrote:

> Not sure if the exception occurs at the commit/detach phase of a request.
> The session is always verified before generating the page content. See the
> stack trace:
>  [m.p.BasePage]
> edu.washington.cac.myuw.servlet.session.NoExistingSessionException: An
> existing user but the HttpSession is null
>        at edu.washington.cac.myuw.servlet.session.UwSession.<init>(Unknown
> Source)
>        at myuw.sessiono.MyUWSession.<init>(Unknown Source)
>        at myuw.session.MyuwSession.setMyUWSession(Unknown Source)
>        at myuw.page.BasePage.setMyUWSession(Unknown Source)
>        at myuw.page.BasePage.setup(Unknown Source)
>        at myuw.page.Main.<init>(Unknown Source)
>        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native
> Method)
>        at
> sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
>        at
> sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
>        at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
>        at
> org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:173)
>        at
> org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:97)
>        at
> org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:47)
>        at
> org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:107)
>        at
> org.apache.wicket.request.handler.PageProvider.resolvePageInstance(PageProvider.java:264)
>        at
> org.apache.wicket.request.handler.PageProvider.getPageInstance(PageProvider.java:165)
>        at
> org.apache.wicket.request.handler.ListenerInterfaceRequestHandler.getPage(ListenerInterfaceRequestHandler.java:100)
>        at
> org.apache.wicket.request.handler.ListenerInterfaceRequestHandler.respond(ListenerInterfaceRequestHandler.java:165)
>
>
> -----Original Message-----
> From: Dan Retzlaff [mailto:dretzlaff@gmail.com]
> Sent: Wednesday, December 07, 2011 4:01 PM
> To: users@wicket.apache.org
> Subject: Re: ConcurrentModificationException
>
> So it sounds like
> 1. you've introduced a custom layer between Wicket and the servlet session,
> 2. that custom layer can throw an exception called InvalidSession while
> Wicket tries to save a page into it (during request cycle commit/detach),
> and
> 3. that exception gets into a handleException() method which calls
> setResponsePage, adding a new request handler to the request cycle being
> detached.
>
> If that's right, then it's probably worth mentioning that the commit/detach
> phase of a request is way too late to be changing response pages. The best
> you can do at that point is log an exception.
>
> (Apologies if I misunderstand you; it sounds fairly unconventional but
> maybe I just haven't pieced it together correctly.)
>
> On Wed, Dec 7, 2011 at 3:05 PM, Fang Lin <Fanglin@u.washington.edu> wrote:
>
> > That's very helpful. Thanks for sharing your code!
> >
> > We use a custom session manager, which verifies the session. When the
> > underline HttpSession is expired, it throws a sub-class of InvalidSession
> > exception.
> >
> > All the Throwable in the WebPage is handled by this method:
> > protected void handleException(Throwable e)
> >  {
> >    if (e instanceof InvalidSession) {
> >      setResponsePage(new SessionErr());  // <== gets triggered before
> > Wicket's PageExpiredException
> >      return;
> >    }
> >    ErrPage.logErr (getLoggerId(),
> >                    e.toString(),
> >                    getHttpServletRequest());
> >    if (e instanceof ParameterException) {
> >      setResponsePage(new ParamErr());
> >      return;
> >    }
> >    setResponsePage(new InternalErr());
> >    return;
> >  }
> >
> >
> > public class SessionErr extends WebPage  {
> >   public SessionErr ()
> >  {
> >    super ();
> >     getRequestCycle().replaceAllRequestHandlers (new
> SessionErrHandler());
> >  }
> > }
> >
> > public class SessionErrHandler extends RedirectRequestHandler {
> >  public SessionErrHandler()
> >  {
> >    super(LOG_BACKIN_URL);
> >   }
> > }
> >
> >
> >
> >
> > -----Original Message-----
> > From: Dan Retzlaff [mailto:dretzlaff@gmail.com]
> > Sent: Wednesday, December 07, 2011 1:56 PM
> > To: users@wicket.apache.org
> > Subject: Re: ConcurrentModificationException
> >
> > If you want to get to the bottom of that CME, then I'd investigate usage
> #1
> > since you've presented usages #2 and #3 and they look okay (barring a
> > Wicket bug).
> >
> > In any case, I haven't been working with 1.5 very long but for what it's
> > worth we have this as our custom RequestCycleListener:
> > http://pastebin.com/SnS9PS8N
> >
> > Note that returning null allows Wicket to employ the registered
> > PageExpiredErrorPage and AccessDeniedPage pages, and we set both to our
> > Login page. The ErrorPage is our customized "oops" page for truly
> > unexpected exceptions.
> >
> > On Wed, Dec 7, 2011 at 1:36 PM, Fang Lin <Fanglin@u.washington.edu>
> wrote:
> >
> > > Hi Dan,
> > >
> > >
> > >
> > > Thanks for the response and the question!
> > >
> > >
> > >
> > > I have put exception handler in three places:
> > >
> > >
> > >
> > > 1. In the WebPage via a try and catch
> > >
> > >
> > >
> > > 2. In the custom RequestCycleListener
> > >
> > >
> > > 3.   In the ApplicationSettings
> > >
> > >
> > >
> > > Because I wasn't clear about the relationship between them, I put them
> > > everywhere just in case. I was also wondering why handler got invoked
> > twice.
> > >
> > >
> > >
> > > It looks like #2 and #3 are unnecessary/redundant unless they handles
> > > different exceptions.
> > >
> > > What would be the recommended approach for exception handling?
> > >
> > >
> > >
> > > -Fang
> > >
> > > -----Original Message-----
> > > From: Dan Retzlaff [mailto:dretzlaff@gmail.com]
> > > Sent: Wednesday, December 07, 2011 9:40 AM
> > > To: users@wicket.apache.org
> > > Subject: Re: ConcurrentModificationException
> > >
> > >
> > >
> > > Hi Fang,
> > >
> > >
> > >
> > > Are there any other references to SessionErr page in your application
> > aside
> > >
> > > from its registration in ApplicationSettings? I ask because, as Martin
> > >
> > > says, Wicket will only instantiate the PageExpiredErrorPage as a
> default
> > >
> > > behavior if a custom RequestCycleListener does not provide an alternate
> > >
> > > handler. Since your RequestCycleListener *always* provides a handler, I
> > >
> > > don't see how the default behavior can apply.
> > >
> > >
> > >
> > > Even more confusing is how you can get CME at that location. It's like
> > the
> > >
> > > SessionErr instantiation happens during the detach process. I'm just
> not
> > >
> > > seeing how Wicket can do that itself.
> > >
> > >
> > >
> > > Dan
> > >
> > >
> > >
> > > On Tue, Dec 6, 2011 at 4:47 PM, Fang Lin <Fanglin@u.washington.edu>
> > wrote:
> > >
> > >
> > >
> > > > Should I use scheduleRequestHandlerAfterCurrent instead of
> > >
> > > > replaceAllRequestHandlers ?
> > >
> > > >
> > >
> > > > -----Original Message-----
> > >
> > > > From: Fang Lin [mailto:Fanglin@u.washington.edu]
> > >
> > > > Sent: Tuesday, December 06, 2011 3:39 PM
> > >
> > > > To: users@wicket.apache.org
> > >
> > > > Subject: RE: ConcurrentModificationException
> > >
> > > >
> > >
> > > > I have just run into the ConcurrentModificationException on my dev
> > > server.
> > >
> > > > Not that I can reproduce it, but I got more details:
> > >
> > > >
> > >
> > > > 1. my session has expired
> > >
> > > >
> > >
> > > > 2. the PageExpiredErrorPage SessionErr was invoked.  Internally it
> > >
> > > > executed this statement:
> > >
> > > >  public SessionErr ()
> > >
> > > >  {
> > >
> > > >    super ();
> > >
> > > >    log.info ("Before replaceAllRequestHandlers");
> > >
> > > >     getRequestCycle().replaceAllRequestHandlers (new
> > > SessionErrHandler());
> > >
> > > >  // <===========
> > >
> > > >   }
> > >
> > > >
> > >
> > > > 3.  SessionErrHandler was created,
> > >
> > > >  public SessionErrHandler()
> > >
> > > >  {
> > >
> > > >    super(LOG_BACKIN_URL);
> > >
> > > >    log.info ("RedirectRequest");
> > >
> > > >  }
> > >
> > > >
> > >
> > > > Log:
> > >
> > > > INFO 06 15:23:58.755 Before replaceAllRequestHandlers
> [m.p.SessionErr]
> > >
> > > > INFO 06 15:23:58.755 RedirectRequest [m.SessionErrHandler] INFO 06
> > >
> > > > 15:23:58.760 Before replaceAllRequestHandlers [m.p.SessionErr] INFO
> 06
> > >
> > > > 15:23:58.760 RedirectRequest [m.SessionErrHandler]
> > >
> > > >
> > >
> > > > On the browser, HTTP Status 500 -
> > >
> > > > java.util.ConcurrentModificationException
> > >
> > > >
> > >
> > > >
> >  java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
> > >
> > > >        java.util.AbstractList$Itr.next(AbstractList.java:343)
> > >
> > > >
> > >
> > > >
> > >
> >
>  org.apache.wicket.request.RequestHandlerStack.detach(RequestHandlerStack.java:176)
> > >
> > > >
> > >
> > > >
> > >
> >
>  org.apache.wicket.request.cycle.RequestCycle.onDetach(RequestCycle.java:565)
> > >
> > > >
> > >
> > > >
> > >
> >
>  org.apache.wicket.request.cycle.RequestCycle.detach(RequestCycle.java:508)
> > >
> > > >
> > >
> > > >
> > >
> >
>  org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:284)
> > >
> > > >
> > >
> > > >
> > >
> >
>  org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:162)
> > >
> > > >
> > >
> > > >
> > >
> >
>  org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:218)
> > >
> > > >
> > >
> > > > -----Original Message-----
> > >
> > > > From: Fang Lin [mailto:Fanglin@u.washington.edu]
> > >
> > > > Sent: Tuesday, December 06, 2011 2:06 PM
> > >
> > > > To: users@wicket.apache.org
> > >
> > > > Subject: RE: ConcurrentModificationException
> > >
> > > >
> > >
> > > > I have been trying to reproduce it on our dev server this morning,
> but
> > >
> > > > could not. However I did run into it twice on our production server
> > >
> > > > yesterday.
> > >
> > > >
> > >
> > > > I wonder if you could answer my question  "Is this exception handler
> > >
> > > > invoked before or after the ErrorPages ?"
> > >
> > > >
> > >
> > > > -----Original Message-----
> > >
> > > > From: Martin Grigorov [mailto:mgrigorov@apache.org]
> > >
> > > > Sent: Tuesday, December 06, 2011 12:47 PM
> > >
> > > > To: users@wicket.apache.org
> > >
> > > > Subject: Re: ConcurrentModificationException
> > >
> > > >
> > >
> > > > No, I don't see anything wrong here.
> > >
> > > > If you are able to reproduce it then we can debug it.
> > >
> > > >
> > >
> > > > On Tue, Dec 6, 2011 at 9:40 PM, Fang Lin <Fanglin@u.washington.edu>
> > > wrote:
> > >
> > > > > Thanks, Martin!
> > >
> > > > >
> > >
> > > > > In the init(), I have:
> > >
> > > > > {
> > >
> > > > >   getMarkupSettings().setStripWicketTags(true);
> > >
> > > > >
> > >
> > > > >    IApplicationSettings settings = getApplicationSettings();
> > >
> > > > >    settings.setAccessDeniedPage(AccessErr.class);
> > >
> > > > >    settings.setPageExpiredErrorPage(SessionErr.class);
> > >
> > > > >    settings.setInternalErrorPage(InternalErr.class);
> > >
> > > > >
> > >
> > > > >    // #2 starts
> > >
> > > > >     getRequestCycleListeners().add(new
> AbstractRequestCycleListener()
> > >
> > > > > {
> > >
> > > > >
> > >
> > > > >        public IRequestHandler onException(RequestCycle cycle,
> > >
> > > > > Exception e)
> > >
> > > > >        {
> > >
> > > > >          return new RedirectRequestHandler (ERROR_PAGE_URL);
> > >
> > > > >        }
> > >
> > > > >      });
> > >
> > > > >    // #2 ends
> > >
> > > > > }
> > >
> > > > > Could the #2 code block be the cause?  Is this exception handler
> > > invoked
> > >
> > > > before or after the ErrorPages ?
> > >
> > > > >
> > >
> > > > > Our authentication strategy is set up at Apache level.
> > >
> > > > > This is what SessionErr class does:
> > >
> > > > > getRequestCycle().replaceAllRequestHandlers (new
> > SessionErrHandler());
> > >
> > > > >
> > >
> > > > > And SessionErrHandler redirect to the Login Servlet. And the Login
> > >
> > > > Servlet will be routed to the WebLogin server.
> > >
> > > > >
> > >
> > > > > -----Original Message-----
> > >
> > > > > From: Martin Grigorov [mailto:mgrigorov@apache.org]
> > >
> > > > > Sent: Monday, December 05, 2011 11:59 PM
> > >
> > > > > To: users@wicket.apache.org
> > >
> > > > > Subject: Re: ConcurrentModificationException
> > >
> > > > >
> > >
> > > > > Hi,
> > >
> > > > >
> > >
> > > > > I don't see how this may happen.
> > >
> > > > > The execution of RequestCycle is single threaded.
> > >
> > > > > Do you have RequestCycleListener or something similar where you
> start
> > >
> > > > another thread and you use the same instance of RequestCycle ?
> > >
> > > > >
> > >
> > > > > On Tue, Dec 6, 2011 at 2:31 AM, Fang Lin <Fanglin@u.washington.edu
> >
> > >
> > > > wrote:
> > >
> > > > >> When clicking on a link (i.e., ?5-1.ILinkListener-...) after
a
> > session
> > >
> > > > expired, this error page shows up on my browser window:
> > >
> > > > >> Exception report
> > >
> > > > >> message
> > >
> > > > >> description The server encountered an internal error () that
> > prevented
> > >
> > > > it from fulfilling this request.
> > >
> > > > >> exception
> > >
> > > > >> java.util.ConcurrentModificationException
> > >
> > > > >>
> > >
> > > > >>
> > java.util.AbstractList$Itr.checkForComodification(AbstractList.java:3
> > >
> > > > >> 7
> > >
> > > > >> 2)
> > >
> > > > >>
> > >
> > > > >> java.util.AbstractList$Itr.next(AbstractList.java:343)
> > >
> > > > >>
> > >
> > > > >>
> > org.apache.wicket.request.RequestHandlerStack.detach(RequestHandlerSt
> > >
> > > > >> a
> > >
> > > > >> ck.java:176)
> > >
> > > > >>
> > >
> > > > >>
> > org.apache.wicket.request.cycle.RequestCycle.onDetach(RequestCycle.ja
> > >
> > > > >> v
> > >
> > > > >> a:565)
> > >
> > > > >>
> > >
> > > > >>
> > org.apache.wicket.request.cycle.RequestCycle.detach(RequestCycle.java:
> > >
> > > > >> 508)
> > >
> > > > >>
> > >
> > > > >>
> > org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(
> > >
> > > > >> R
> > >
> > > > >> equestCycle.java:284)
> > >
> > > > >>
> > >
> > > > >>
> > org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFil
> > >
> > > > >> t
> > >
> > > > >> er.java:162)
> > >
> > > > >>
> > >
> > > > >>
> > org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.ja
> > >
> > > > >> v
> > >
> > > > >> a:218)
> > >
> > > > >>         at
> > >
> > > > >>
> > org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
> > >
> > > > >> i
> > >
> > > > >> cationFilterChain.java:235)
> > >
> > > > >>        at
> > >
> > > > >>
> > org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
> > >
> > > > >> i
> > >
> > > > >> lterChain.java:206)
> > >
> > > > >>        at
> > >
> > > > >>
> > org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
> > >
> > > > >> a
> > >
> > > > >> lve.java:233)
> > >
> > > > >>        at
> > >
> > > > >>
> > org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
> > >
> > > > >> a
> > >
> > > > >> lve.java:191)
> > >
> > > > >>        at
> > >
> > > > >>
> > org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.j
> > >
> > > > >> a
> > >
> > > > >> va:127)
> > >
> > > > >>        at
> > >
> > > > >>
> > org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j
> > >
> > > > >> a
> > >
> > > > >> va:102)
> > >
> > > > >>        at
> > >
> > > > >>
> > org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal
> > >
> > > > >> v
> > >
> > > > >> e.java:109)
> > >
> > > > >>        at
> > >
> > > > >>
> > org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.jav
> > >
> > > > >> a
> > >
> > > > >> :298)
> > >
> > > > >>        at
> > >
> > > > >>
> > org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190)
> > >
> > > > >>        at
> > >
> > > > >>
> org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:291)
> > >
> > > > >>        at
> > >
> > > > >> org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:774)
> > >
> > > > >>        at
> > >
> > > > >>
> > org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.ja
> > >
> > > > >> v
> > >
> > > > >> a:703)
> > >
> > > > >>        at
> > >
> > > > >>
> > org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSock
> > >
> > > > >> e
> > >
> > > > >> t.java:896)
> > >
> > > > >>        at
> > >
> > > > >>
> > org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadP
> > >
> > > > >> o
> > >
> > > > >> ol.java:690)
> > >
> > > > >>        at java.lang.Thread.run(Thread.java:662)
> > >
> > > > >> This ConcurrentModificationException occurs about 70+ times on
an
> > >
> > > > application server daily.
> > >
> > > > >> Wicket version 1.5.3.
> > >
> > > > >> Any suggestion on how to avoid this?
> > >
> > > > >> In the init method of sub-class of the WebApplication , I have:
> > >
> > > > >>   IApplicationSettings settings = getApplicationSettings();
> > >
> > > > >>    settings.setAccessDeniedPage(AccessErr.class);
> > >
> > > > >>    settings.setPageExpiredErrorPage(SessionErr.class);
> > >
> > > > >> settings.setInternalErrorPage(InternalErr.class);
> > >
> > > > >> When a session expired, should it invoke the PageExpiredErrorPage?
> > >
> > > > >
> > >
> > > > > Yes. You make a request to a page, Wicket searches for this page
in
> > the
> > >
> > > > stores, doesn't find it and throws PageExpiredException.
> > >
> > > > > But, if the request url has the mount path then Wicket will create
> a
> > > new
> > >
> > > > Page instance instead. If you have authentication strategy set up
> then
> > > you
> > >
> > > > go to the Login page, otherwise this page will be rendered.
> > >
> > > > >
> > >
> > > > > If you are able to reproduce the problem in a quickstart attach it
> to
> > >
> > > > Jira so we can debug it.
> > >
> > > > > Thanks!
> > >
> > > > >
> > >
> > > > >> -Fang
> > >
> > > > >>
> > >
> > > > >>
> > >
> > > > >
> > >
> > > > >
> > >
> > > > >
> > >
> > > > > --
> > >
> > > > > Martin Grigorov
> > >
> > > > > jWeekend
> > >
> > > > > Training, Consulting, Development
> > >
> > > > > http://jWeekend.com
> > >
> > > > >
> > >
> > > > >
> ---------------------------------------------------------------------
> > >
> > > > > To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
> > >
> > > > > For additional commands, e-mail: users-help@wicket.apache.org
> > >
> > > > >
> > >
> > > >
> > >
> > > >
> > >
> > > >
> > >
> > > > --
> > >
> > > > Martin Grigorov
> > >
> > > > jWeekend
> > >
> > > > Training, Consulting, Development
> > >
> > > > http://jWeekend.com
> > >
> > > >
> > >
> > > > ---------------------------------------------------------------------
> > >
> > > > To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
> > >
> > > > For additional commands, e-mail: users-help@wicket.apache.org
> > >
> > > >
> > >
> > > >
> > >
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
> > For additional commands, e-mail: users-help@wicket.apache.org
> >
> >
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
> For additional commands, e-mail: users-help@wicket.apache.org
>
>

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