[ZODB-Dev] Re: BTrees strangeness (was [Zope-dev] Zope 2.X BIG Session problems - blocker - our site dies - need help of experience Zope developer, please)

[Dieter Maurer]

Hi Chris,

Chris McDonough wrote at 2004-5-11 00:54 -0400:
> ...
>So what do folks think of this error-case transaction isolation patch? 
>Michael's original patch is preserved here (although it didn't survive
>cut and paste from my mail client in a pristine way, you'll get the
>idea):
>
>http://www.plope.com/Members/chrism/transaction_isolation_error.patch/file_view
>
>Personally it looks fine to me.  It wraps each error invocation in its
>own transaction.

Please revisit the discussion (mostly between Toby and me) on
"zope-dev" about how to fix this problem.

Toby convinced me that error handling should take place
in the same transaction as the original request (and not in its
own).

His main argument: the traceback can contain references to persistent
objects that should not be there. If they are written to ZODB
in any way, all kinds of dubious inconsistencies can occur.

Meanwhile, I saw several questions in the mailing lists of
people that wanted to access the SESSION object during
error handling (probably) because it contained useful information for
error handling.
This is impossible when the transaction is aborted before
error handling.

-- 
Dieter