Hi Martin, yes we are on 6. I've just spent the day upgrading to 7 and got it running ok. I've been debugging and I'm confused to one aspect:
The PageManager is stored in the Application. The page manger has the RequestAdaptor/PageStoreManager stored within that holds the pages and components. I observe that when a new instance joins the cluster this pagestoremanager SessionEntry is serialized across to the new instance. However further requests do NOT serialise the session entry across. If the original node is then shutdown, on the new instance the page (from the further requests) cannot be found in the pagestoremanager (its bookmarkable page) and a new instance must be constructed instead. This is where I get the problem as it can't find the component on the new instance (I'm still debugging why this is the case). However my question is whats the point of serialising across the SessionEntry if its not done on each session commit? Its only of use if the node is stop straight after the new instance is started. thanks On Tue, Mar 28, 2017 at 9:39 PM, Martin Grigorov <[email protected]> wrote: > Hi, > > Did you mention already which version of Wicket you use ? > There was an improvement related to reusing the page parameters when > constructing a new page instance in 7.0.0. > I have the feeling you are using 6.x. Am I correct ? > > Martin Grigorov > Wicket Training and Consulting > https://twitter.com/mtgrigorov > > On Tue, Mar 28, 2017 at 7:22 PM, Wayne W <[email protected]> > wrote: > > > Hello Martin, > > > > so I've been trying to still get to the bottom of this days later. So my > > understanding is getting better and it appears that the session itself is > > replicated fine. However I've tracked my issue down to the following: > > > > - If I have a page that has 2 links at the top. Link A is a Bookmarkable > > link back to the same page - it is also mounted thus: mountPage( > > "/cube/documents/${0}", CubeDocumentPage.class); It has a Long page param > > needed to construct the page ( i.e. /cube/documents/12345 ). The second > > link B is just a simple new Link<Void>("B") . > > - If both instances are up and running , lets say I am on instance A. I > > visit link A 3 times. I then kill instance A and I am balanced over to > > instance B. If I visit link B , the PageStoreManager cannot find the > page > > that contains link B in the store and then tries to create a new instance > > of the page - the problem is then for some reason the page parameters are > > always null and the Long is never passed. Why is the page parameter > always > > null here? Trying to debug it, is seems the IPageManager is got from the > > wicket Application instance and not the Session, and this IPageManager > > looks for a RequestAdaptor. Somewhere the page parameters are lost?. > > > > However I can get it to work this way: > > - start instance A, visit the page and say click link A 3 times. > > - Now start up instance B > > - Kill instance A > > - Click on the link B and this time the PageStoreManager finds the page > and > > there the link B and everything works fine. > > It only works if I don't visit another page just after instance B starts > > up. > > > > > > I will do some more debugging tomorrow to try and understand this > > PageStoreManager/request adaptor bit more. But if you have any ideas I'd > > appreciate it. > > Thanks > > > > > > > > On Fri, Mar 24, 2017 at 12:48 PM, Martin Grigorov <[email protected]> > > wrote: > > > > > Hi, > > > > > > On Fri, Mar 24, 2017 at 1:31 PM, Wayne W <[email protected]> > > > wrote: > > > > > > > Thanks Martin, > > > > > > > > I have a theory what this is, perhaps you could confirm? > > > > > > > > What I observe is the following with the replication: If I visit > page A > > > and > > > > then visit page B, then kill the instance I am on the session is > > > > successfully failed over to the other node. Now I'm still looking at > > > page B > > > > in the browser - if I hit back on the browser I get > > PageExpiredException. > > > > Is this the expected behaviour? > > > > > > > > > > No. > > > The expected behavior is to see the latest state of page A. > > > > > > > > > > > > > > If it IS the expected behaviour, then the reason I think that I have > an > > > > issue with the page with the AbstractDefaultAjaxBehavior is because > the > > > > code in the AbstractDefaultAjaxBehaviour.respond is adding > components > > to > > > > the page which in turn marks the Session dirty which in turn > replicates > > > the > > > > session. If only the last page/session commit is only replicated it > > could > > > > explain why I get a ComponentNotFound exception from the page as > > > > it overwriten by the update from the AbstractDefaultAjaxBehavior > > > > > > > > > > Any time the page is marked as dirty Wicket will store it in 1) the > HTTP > > > session and 2) on the disk > > > 1) will notify the web server (e.g. Tomcat) that it has to replicate > the > > > session because some attribute has been modified > > > At node2 Wicket will detect the replicated session in #readObject() and > > > store it on the disk. > > > From now on node2 will have the same history for that page as node1, > i.e. > > > PageA and PageB. > > > > > > In addition: > > > Updates made in an Ajax requests do not add a new entry in the history > > > (storages) but overrides the previous entry for that page instance! > > > I.e. when PageA is rendered Wicket will assign a pageId for it, e.g. 5, > > and > > > store it in the disk. > > > Later when you make a change to PageA:5 in Ajax request then Wicket > will > > > override the entry on the disk. > > > If you make a change in non-Ajax request then Wicket will assign a new > > > pageId, e.g. 6, and add a new entry in the history (disk), so you will > > have > > > two entries for this session. > > > Later when you open PageB then this will be pageId 7, etc. > > > > > > > > > > > > > > What do you think? > > > > > > > > > > > > > > > > On Fri, Mar 24, 2017 at 9:31 AM, Martin Grigorov < > [email protected] > > > > > > > wrote: > > > > > > > > > Hi, > > > > > > > > > > Once the http session is replicated this method should be executed > on > > > the > > > > > node that did not process the request > > > > > org.apache.wicket.page.PageStoreManager.SessionEntry#readObject(). > > > > > Here Wicket will either store the page(s) on the disk or will > > schedule > > > > them > > > > > for storing. > > > > > There is no much usage of Loggers here so you will have to attach a > > > > > debugger and see what happens. > > > > > > > > > > Martin Grigorov > > > > > Wicket Training and Consulting > > > > > https://twitter.com/mtgrigorov > > > > > > > > > > On Thu, Mar 23, 2017 at 6:11 PM, Wayne W < > > [email protected]> > > > > > wrote: > > > > > > > > > > > If I put the AbstractDefaultAjaxBehavior back in, it always > fails. > > > If I > > > > > > remove the AbstractDefaultAjaxBehavior most of the time it works, > > but > > > > > every > > > > > > now and then it fails to replicate. Its really inconsistent. > > > > > > > > > > > > I have no idea how to get to the bottom of this. Any pointers or > > help > > > > is > > > > > > much appreciated. > > > > > > > > > > > > On Thu, Mar 23, 2017 at 4:53 PM, Wayne W < > > > [email protected]> > > > > > > wrote: > > > > > > > > > > > > > So it seems the homepage is not the only page. However removing > > the > > > > > > > AbstractDefaultAjaxBehavior makes no difference I still get the > > > same > > > > > > > issues. Just don;t know where to start with this one. Is there > a > > > way > > > > I > > > > > > can > > > > > > > turn on the logging around replication in wicket? > > > > > > > > > > > > > > On Thu, Mar 23, 2017 at 4:27 PM, Wayne W < > > > > [email protected]> > > > > > > > wrote: > > > > > > > > > > > > > >> Hi Martin, > > > > > > >> > > > > > > >> no - I still get the ComponentNotFoundException in the new > > > instance. > > > > > :-/ > > > > > > >> > > > > > > >> On Thu, Mar 23, 2017 at 3:57 PM, Martin Grigorov < > > > > > [email protected]> > > > > > > >> wrote: > > > > > > >> > > > > > > >>> Hi, > > > > > > >>> > > > > > > >>> On Thu, Mar 23, 2017 at 4:20 PM, Wayne W < > > > > > [email protected]> > > > > > > >>> wrote: > > > > > > >>> > > > > > > >>> > Hi Martin, > > > > > > >>> > > > > > > > >>> > that was a typo on my part. I've been doing a lot more > > testing > > > > > > before I > > > > > > >>> > replied to make sure things are as I say. This is what I am > > > > > > observing: > > > > > > >>> > > > > > > > >>> > > > > > > > >>> > - I have a 2 node tomcat cluster setup with apache > > balancing > > > > > > between > > > > > > >>> > them locally on my machine. > > > > > > >>> > - Testing with a very simple Wicket app I can see the > > > > > replication > > > > > > is > > > > > > >>> > working fine when shutting down either instance. > > > > > > >>> > - Testing with our very heavy weight wicket app it > > sometimes > > > > > work > > > > > > >>> and > > > > > > >>> > sometimes does not. > > > > > > >>> > > > > > > > >>> > Now the last point above I have narrowed down to our > > homepage. > > > > If I > > > > > > am > > > > > > >>> not > > > > > > >>> > on the homepage the replication seems to work ok. However > if > > I > > > am > > > > > on > > > > > > >>> the > > > > > > >>> > homepage I always get a ComponentNotFoundException when > > failing > > > > > over > > > > > > >>> to the > > > > > > >>> > other instance. > > > > > > >>> > The homepage has an AbstractDefaultAjaxBehavior which is > > called > > > > > once > > > > > > >>> the > > > > > > >>> > page is rendered, this in turn adds to the the page a > > DataView > > > > > > >>> containing a > > > > > > >>> > lot of content and links. The user needs to be logged in > > before > > > > > they > > > > > > >>> see > > > > > > >>> > the homepage, so the session is already setup. > > > > > > >>> > > > > > > > >>> > I don't know what it is about this page that breaks the > > > > > replication. > > > > > > Is > > > > > > >>> > there anything around the ajax part that could do this? Any > > > > > pointers > > > > > > >>> would > > > > > > >>> > be most welcome as it will be a long long task to break > that > > > page > > > > > > down > > > > > > >>> and > > > > > > >>> > do rounds and rounds of cluster testing > > > > > > >>> > > > > > > > >>> > > > > > > >>> Let's try something! > > > > > > >>> In you Ajax callback method do something like: > > > > > > >>> getSession().setAttribute("someKey", > > > UUID.randomUUID().toString()) > > > > > > >>> Does this trigger replication ? > > > > > > >>> > > > > > > >>> > > > > > > >>> > > > > > > > >>> > many thanks > > > > > > >>> > > > > > > > >>> > > > > > > > >>> > > > > > > > >>> > > > > > > > >>> > On Wed, Mar 22, 2017 at 12:34 PM, Martin Grigorov < > > > > > > >>> [email protected]> > > > > > > >>> > wrote: > > > > > > >>> > > > > > > > >>> > > Hi, > > > > > > >>> > > > > > > > > >>> > > "I can stop one of the instances and I'm not logged in" > > > > > > >>> > > This statement says that you don't really have a properly > > > > > > configured > > > > > > >>> > > failover. > > > > > > >>> > > If those two Tomcat instances are in a cluster then the > > http > > > > > > sessions > > > > > > >>> > > should be replicated and you should stay logged in no > > matter > > > > > which > > > > > > >>> one is > > > > > > >>> > > serving the request. > > > > > > >>> > > Wicket will store the used stateful page at the disks for > > all > > > > > > >>> Tomcats in > > > > > > >>> > > the cluster, if it the replication is actually working! > > > > > > >>> > > > > > > > > >>> > > > > > > > > >>> > > On Wed, Mar 22, 2017 at 1:02 PM, Wayne W < > > > > > > >>> [email protected]> > > > > > > >>> > > wrote: > > > > > > >>> > > > > > > > > >>> > > > Hi, > > > > > > >>> > > > > > > > > > >>> > > > We have 2 instances of Tomcat running with Apache > sitting > > > in > > > > > > front > > > > > > >>> > > > balancing between the Tomcat instances. I have session > > > > > > replication > > > > > > >>> > setup > > > > > > >>> > > > which seems to work for basic bookmarkable links on the > > > > pages. > > > > > I > > > > > > >>> can > > > > > > >>> > stop > > > > > > >>> > > > one of the instances and I'm not logged in as it > failover > > > to > > > > > the > > > > > > >>> other > > > > > > >>> > > > instance. > > > > > > >>> > > > > > > > > > >>> > > > However for normal Link<?> and ajax links etc I get > > > > > > >>> > > > ComponentNotFoundException thrown as the new instance > > > cannot > > > > > > find > > > > > > >>> it > > > > > > >>> > in > > > > > > >>> > > > the session it seems. > > > > > > >>> > > > > > > > > > >>> > > > Clearly I'm not understanding how wicket manages the > page > > > > state > > > > > > or > > > > > > >>> I've > > > > > > >>> > > > configured something wrong. > > > > > > >>> > > > > > > > > > >>> > > > Does wicket support full session failover ? > > > > > > >>> > > > > > > > > > >>> > > > Many thanks > > > > > > >>> > > > > > > > > > >>> > > > > > > > > >>> > > > > > > > >>> > > > > > > >> > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > > >
