POSKeyErrors was Re: [Zope] Zope leaking memory?

[Chris McDonough]

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.

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.  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 ).  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 ;-).

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).

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.  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. 

- C