[Zope] ODBC and Inserting not committed

[Michel Pelletier]

Graham Chiu wrote:
> 
> Hi,
> 
> With 2b1, win32, I now find that my Zsql inserts don't commit.  They
> last for as long as the browser is active.  I start another browser
> session after closing the first one down, and they're gone.
> 

It's possible, although I have not personally looked at the code, that
the ODBC adapter has not been updated to work with the new ZODB3
transaction manager.

Try running Zope in single thread mode ('-t 1' on the z2.py command
line) and see if the problem persists.  If so, then the ODBC driver will
probably need to be 'thunked' which is a pretty trivial 10 minute change
to the code.

Note that thunking a DA has side effects!  'Thunking' means to wrap the
Zope DA transaction manager in a thread lock.  What this means is that
if a DA is thunked, it will work in a multi-threaded Zope, but all ZSQL
queries will be serialized at the Zope transaction layer *including
queries from other thunked DAs!*  This means that all thunked DAs block
each other at Zope transacion boundaries (Zope transacion boundaries are
usually but not allways, single requests, like an HTTP request).  This
does not apply to completly thread safe (or, level 3) DAs.  To sumarize
the levels:

Level 1: Not threadsafe, concurrent or thunked.  Zope MUST run in single
thread mode

Level 2: Not concurrent, but threadsafe and thunked.  Zope can run in
thread mode

Level 3: Threadsafe and concurrent.  Zope can run in thread mode

Going from level 1 to 2 is usualy trivial.  That I know of, Gadfly and
the soon to be released ZSybaseDA are level 2.  Level 3 is much harder,
and I believe that DCOracle will probably be the first level 3 DA there
is.

-Michel

> Updates seem to commit though.
> 
> Bizarre.
> 
> -------
> Regards,        Graham Chiu
> gchiu<at>compkarori.co.nz
> 
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