POSKeyErrors was Re: [Zope] Zope leaking memory?

[Richard Jones]

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On Wed, 15 Sep 2004 11:09 am, Chris McDonough wrote:
> On Tue, 2004-09-14 at 19:18, Richard Jones wrote:
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> > On Wed, 15 Sep 2004 08:51 am, you wrote:
> > > POSKeyErrors?  Do you know which objects are going missing?
> >
> > BTrees of some sort in every case.
> >
> > Unfortunately, we make use of Transience outside of the regular SESSION
> > stuff (for wizards which include file uploads).
> >
> > Am still working through my daily morning POSKeyError cleanup :(
>
> I haven't seen any reports in the collector of POSKeyError resulting
> from Transience usage.  I presume the BTrees that go missing are
> transience-related?  Even if so I'm not sure if that indicates anything
> is wrong with Transience itself.

My POSKeyErrors all pop up in Transience. Also, my reading of the collector 
reports and related mailing list discussions seemed to indicate that 
sessions, and their Transience stores, were the culprits. I'm very much a 
newbie when it comes to this stuff - I've not had the time (not will I) to 
really dig into it or fully understand what's going wrong. Happy to be told 
I've got it all wrong, just as long as I can eventually (soon would be nice) 
figure out how to *fix* it all :)


> Lately, Tim has made some fixes to ZODB 3.2 (aka Zope 2.7) that cause an
> exception to be raised if a connection is closed while there are pending
> modifications in that connection.

Yep, aware of that.


> Also, another bug has been fixed to 
> make "begin()" to also do an "abort()" even if there are only
> modifications pending in subtransactions within a transaction ( see
> http://zope.org/Collectors/Zope/789
> http://article.gmane.org/gmane.comp.web.zope.zodb/5364 ).

And that.


> Additionally, 
> Zope's publisher has been changed to be more explicit about transaction
> management (required by the first ZODB fix, although its old behavior
> would have left it solved by the second ;-).

And that too ;)


> Aapparently the "abort subtransactions when beginning the main
> transaction" bug can be a source of POSKeyErrors due to
> connection-cache/database desynchronization.  I have no idea if this is
> what is biting you but it's worth a shot to find out I suppose.
>
> All of these fixes have happened recently enough that they haven't yet
> made it to any released Zope version and are only available in CVS (on
> the Zope-2_7-branch).

I've just upgraded my development system to 2-7 branch but a separate issue 
relating to permissions has popped up. Have mailed zope-dev, and hopefully 
that can be resolved ASAP.


> Unrelatedly, new work has also been happening in Transience that will be
> merged into the 2.7 branch soon as well.  This is currently in good
> shape on the 'chrism-pre273-branch' of Transience in CVS.

Yes, been watching those checkins, though I understand none of them. I'm not 
quite desperate enough to run that branch though ;)


> See http://www.plope.com/Members/chrism/sessioning_redux for the list of
> features and bugfixes that have been happening to Transience and friends
> recently.

I'll read up on them, yes. Thanks for the pointer.


     Richard
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