[Zope-CMF] zope hangs

[A Mennucc]

hello

I have experienced a very nasty problem on my site http://dida.sns.it for ~1 year.  

In my site I am using external files, with an ExtFile class that I modified, and a CMF_ExtFile that I prepared. Both products are available in http://tonelli.sns.it/pub/mennucc1/zope/hang/E.tgz

Sometimes, when somebody connects into my site (as member, not as manager) and create those CMF_ExtFile, zope hangs: it does not serve pages any more, that is, browser's requests pend forever. No log is printed. The only solution is to restart zope. Curiosly enough, after restarting, the new object that was created is there.

I have tried to debug zope with the pdb, and I see that the main thread runs ok: it loops in Lifetime.py ; unfortunately I cant understand what is happening in the other threads .  The hang occours ~ 1/4 of the times when I create or delete these objects.
I have also tried to use the ExternalFile and CMFExternalFile (that I included in E.tgz) and I saw the same problem.

The problem was occurring with zope 2.6.2 plone 1.0.5 cmf 1.3 and python 2.1
I have upgraded then to zope 2.7.0 plone 2.0 and cmf from plone.... and the problem seems even worse.

I have tried to trigger the problem by creating/deleting ExtFiles in the ZMI, but it never happened: it only happens when working with the CMF_ExtFile inside Plone. This is why I am posting this bug in this list.

I have been able to reproduce the problem in a fresh install of zope on my notebook: 
- install zope 2.7.0 (my package is in http://tonelli.sns.it/pub/mennucc1/zope/debian/sid )
- unpacked CMFPlone-2.0-final.tar.gz and E.tgz  in an instance
- created a Plone site, and added a member
- installed CMF_Mennucc and CMFExternalFile using the quickinstall tool
- created <instance>/externalfiles <instance>/var/reposit
- played as a member , adding and removing the above objects many times

I need help badly: I have tried to track the bug for 10 days, with no success. 
(I would be very happy to learn at least  a way to unlock zope w/o restarting it.)

a.

-- 
Andrea Mennucc
 "one houndred and fifty - the chicken sings"