[Zope] Inavlid Refernce Counts in Temporary Storage

Philip Kilner phil at xfr.co.uk
Thu Jul 13 10:30:36 EDT 2006

Hi All,

I have an RDBMS application, which resides in a Plone site, but uses
only Zope techniques.

Aside from Plone, the only use of the ZODB is to hold session variables
for users (search parameters etc.), and the load on that part of the
system is very light (10 users, accessing the script in question once
every couple of minutes at the most). The session variables are written
by simple TTW Python scripts, and read back by TALES expressions - all
very simple.

For the last three days, we have been plagued by slowdowns and temporary
lock-ups, which have on a couple of score occasions culminated in a
Conflict Error, indicting transactional problems in the temporary
storage. On four or five occasions, Zope has apparently "locked up", and
a restart has been required.

Today, I am seeing errors when I try to pack this storage: -

2006-07-13T15:09:11 ERROR Zope.SiteErrorLog
Traceback (most recent call last):
 File "D:\PROGRA~1\ENFOLD~1\Zope\lib\python\ZPublisher\Publish.py",
line 114, in publish
   request, bind=1)
 File "D:\PROGRA~1\ENFOLD~1\Zope\lib\python\ZPublisher\mapply.py",
line 88, in mapply
   if debug is not None: return debug(object,args,context)
 File "D:\PROGRA~1\ENFOLD~1\Zope\lib\python\ZPublisher\Publish.py",
line 40, in call_object
   result=apply(object,args) # Type s<cr> to step into published object.
 File "D:\Program Files\Enfold
Server\Zope\lib\python\App\ApplicationManager.py", line 426, in
 File "D:\PROGRA~1\ENFOLD~1\Zope\lib\python\ZODB\DB.py", line 634, in pack
   self._storage.pack(t, referencesf)
line 350, in pack
line 321, in _takeOutGarbage
   raise ReferenceCountError, (
ReferenceCountError:  An error occured while decrementing a reference
to an object in
   the commit phase. The object's reference count was below zero.
(Oid '\x00\x00\x00\x00\x00\x00\x00;' had refcount -1)

This seems to indicate that the temporary storage is corrupt in some way
- am I right?

If so, what do I do about it?

Could this indicate a RAM or disk problem, since the application has not
changed significantly, at least at the level of my TTW code?

Any input welcome - aside from this simple use of the session, I never
have to manipulate the ZODB, so this is pretty new to me!




"Human language continually changes, innit."
- Stephen Juan

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