To clean out a hibernate session:
s.clear();
That will clean everything out of it. Be warned though that it
clears *everything* out of it, not just the stuff you recently loaded. A
safer way is to evict each object one at a time as you load it e.g.
Sesison s = HibHelper.getSession();
Query q = s.createQuery("from bigList");
List l = q.list();
For (int x=0; x< l.size(); x++)
s.evict(l.get(x));
> -----Original Message-----
> From: seloha . [mailto:[EMAIL PROTECTED]
> Sent: Monday, September 26, 2005 12:45 PM
> To: tapestry-user@jakarta.apache.org
> Subject: RE: OutOfMemoryError Tapestry 4.0
>
> Pat,
>
> 1) Yes I am setting the object list to null.
>
> 2) I have not put a log statement in the code to check it but I have set a
> break point in debug mode and each time the page was rendered the code in
> pageDetached(PageEvent event) was run.
>
> 3) There is no other code which references the list object except the
> rendering using the For component.
>
> 4) Subsequent to adding the pageDetached(PageEvent event) I have not run
> it
> on with the caching enabled. This I will do next.
>
> 5) I am using hibernate for the persistent layer. I have always just let
> Spring look after the hibernate session using declarative transactions and
> have never bypassed this mechanism. How do I evict go about evicting the
> objects after the transaction which picks them up. Can I just write a
> piece
> of code in my DAO which after picking the objects up then has something
> like:
>
> getHibernateTemplate().evict(objects);
>
> As you can see I am fairly nieve about use of hibernate too.
>
>
> Thanks,
>
> Paul
>
>
> Patrick Casey <[EMAIL PROTECTED]> wrote:
>
> Well, it really smells to me like a leak, largely because 5,000
> objects, while a pain in the posterior to scroll through, is mouse nuts
> from
> a memory use standpoint (say each object is 10k (a whopper of an object),
> we're only looking at 50 M of memory here. Most object though are at least
> an order of magnitude smaller than that.
>
> Just to reinterate though:
>
> It loads once fine.
> If you keep loading the page, eventually you get an EOM error,
> right?
>
> Some other things to look at:
>
> 1) Unless Howard changed things or I'm remembering wrong, initial-value
> *does not* reset object to that state. Rather it's the value at page
> creation, not the value that something gets set to when a page goes into
> or
> out of the pool. So to null something out after render, you need to
> explicitly set it to null in the detach code (as it appears you are
> doing).
>
> 2) Can you put a log statement or something similar in your page detatch
> listener to make sure it's being called? I don't know how many times I got
> bit by adding PageBeginRender methods to Tap 3 forms without remembering
> to
> add implements PageEventListener to the class.
>
> 3) Are there any other object (statics, the visit object, some other
> property on the page) which reference your object chain?
>
> 4) Do you still get the EOM with tapestry's cache turned off? If so, it's
> not your tapestry code that's hanging onto a reference. If not, then the
> problem lies in not re-iniitalizing something properly before a page goes
> back into the pool.
>
> 5) Are you using Hibernate as your persistence layer? If so, are you
> evicting these objects out of the session and/or loading them in a temp
> session which you are subsequently closing? Objects loaded in a Hibernate
> session have the lifespan of the session, regardless of whether or not
> your
> code holds a reference to them.
>
>
>
> >-----Original Message-----
> >From: seloha . [mailto:[EMAIL PROTECTED]
> >Sent: Monday, September 26, 2005 11:55 AM
> >To: tapestry-user@jakarta.apache.org
> >Subject: RE: OutOfMemoryError Tapestry 4.0
> >
> >Thanks Pat,
> >
> >One thing I was not doing which you pointed out was setting the list to
> >null
> >in pageDetached(PageEvent event) so I added this and also included
> >System.gc(). This unfortunately had no affect. The list uses abstract
> >getter
> >and setter and is initialized in the .page spec with
> >initial-value="ognl:null".
> >
> >I have a number of selection models for PropertySelection components
> which
> >are initialized lazily which I am not resetting to null each time (but
> >there
> >are only about 100 total items in these objects). Could these have any
> >affect.
> >
> >I am really poking around in the dark. Similar Spring and Hibernate
> >mechanism that I wrote using Tapestry 3.0.3 is on a production system and
> >has run with no problems for months. Admittedly I never go and display
> >5000
> >objects at once though!
> >
> >I cannot see that I am inadvertently holding onto any objects in the code
> >but you never know?
> >
> >Thanks again for your help,
> >
> >Paul
> >
> >
> >Patrick Casey <[EMAIL PROTECTED]> wrote:
> >
> > It sounds like a memory leak, but it could just be a slow garbage
> >collector as well. Try adding:
> >
> > System.gc() to the end of your transaction to guarantee the garbage
> >collector runs after each page render. Then see if repeated page renders
> >still blow out your memory. If they do, then I suspect that somehow you
> >(or
> >tapestry, or spring) is hanging onto a reference to those object after
> >page
> >completion.
> >
> > --- Pat
> >
> > PS You *are* resetting your page properties to null (and nulling out
> >the list of 5000 items) on the page's post-render cleanup phase, right?
> >
> > >-----Original Message-----
> > >From: seloha . [mailto:[EMAIL PROTECTED]
> > >Sent: Monday, September 26, 2005 3:11 AM
> > >To: tapestry-user@jakarta.apache.org
> > >Subject: OutOfMemoryError Tapestry 4.0
> > >
> > >I have a page which allows a user to search the database based on
> various
> > >criteria. I have restricted the number of returned items to 5000. I
> > >display
> > >the items in the same search page using the @For component with
> > >volatile="ognl:true" . Repeated searches which return 5000 items will
> > >result
> > >in an OutOfMemoryError exception. If I leave the page and then return
> or
> > >stay on the page I will ultimately get an OutOfMemoryError exception.
> > >
> > >I can view other pages after this exception but a repeat of trying to
> > >display 5000 items on this page will display an OutOfMemory exception.
> > >
> > >The only way to clear this problem is to restart the servlet container.
> > >This
> > >fails using either Jetty or Tomcat in both development and production
> > >environments (using different operating systems).
> > >
> > >All the variables displaying the list are explicitly declared in the
> >.page
> > >specification and using initial-value set to null.
> > >
> > >I am using Tapestry 4.0 beta 8.
> > >
> > >The data is retrieved using Spring and Hibernate (no fancy patterns,
> > >standard Spring declarative transactions and using
> >getHibernateTemplate())
> > >and mapped to Tapestry using hivemodule.xml:
> > >
> > > <implementation service-
> > >id="hivemind.lib.DefaultSpringBeanFactoryHolder">
> > > <invoke-factory>
> > > <construct autowire-services="false"
> > >class="uk.co.cymbol.tair.tapestry.AppSpringBeanFactoryHolderImpl">
> > > <event-listener service-id="hivemind.ShutdownCoordinator" />
> > > <set-object property="context"
> > >value="service:tapestry.globals.WebContext" />
> > > </construct>
> > > </invoke-factory>
> > > </implementation>
> > >
> > >and injecting the appropriate Spring bean.
> > >
> > >I am completely confused as to how to tie down the problem and isolate
> > >which
> > >section of code is causing the problem.
> > >
> > >Any help would be much appreciated.
> > >
> > >Paul
> > >
> > >
> > >
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