ZODB3 3.3 alpha 2 released

[Jeremy Hylton]

I'm pleased to announce the release of ZODB2 3.3 alpha 2.  This release
includes support for new-style persistent classes and multi-version
concurrency control.  It's an alpha release, so we could use feedback on
the new features and helping testing them.

The 3.3a2 release requires Python 2.3.  It contains the code that is
slated to be in Zope 2.8.

You can download a source tarball or Windows installer from
http://zope.org/Products/ZODB3.3

The new features represent major changes to ZODB.  Support for new-style
classes means that ZODB programmers can use the new class features
introduced in Python 2.2, like properties and descriptors.  It also
means that ZODB no longer uses ExtensionClass, which caused many subtle
incompatibilities with other classes.

The multi-version concurrency control feature represents the end of read
conflicts.  If a transaction encounters a conflict, it reads older
revisions of the object rather than raising a ReadConflictError.  This
feature allows read-only transactions to see a consistent view of the
database without need to handle read conflicts and restart the
transaction.

The code is fairly stable, but we have noted a few hard-to-provoke bugs
during development.  One problem is a refcount problem in the
persistence core that causes rare core dumps in Python's garbage
collector.  (Rare means once a week across multiple developers and
testers.)

We hope to move to a beta release expeditiously, perhaps as early as
next month.  The final release schedule depends on the Zope 2.8 release
schedule.  More on that later.

Enjoy!

-- Jeremy Hylton <http://www.python.org/~jeremy/>