[Catalog-sig] Untested patch for PyPI exceptions

"Martin v. Löwis" martin at v.loewis.de
Sun May 6 10:35:52 CEST 2007

A.M. Kuchling schrieb:
> The completely untested patch below should remedy the occasional
> exceptions that PyPI is occasionally raising.  Can someone provide a
> sanity check for this patch?  (I'm not going to deploy it -- not
> familiar enough with the setup on the live site.)

I don't understand why this is necessary (although I trust that these
exceptions really occur).

Can any expert on Postgres please shed a light on it? The code currently

        self.cursor.execute("lock table browse_tally")
        if self.is_cache_current():
            # overlapping update, just release the lock
        self.cursor.execute("delete from browse_tally")
        self.cursor.execute("update timestamps set value=now() where

Now, this code gets an exception

psycopg.ProgrammingError: ERROR:  could not serialize access due to
concurrent update

delete from browse_tally

How is that possible? This code is the only code code updating
browse_tally (although multiple simultaneous processes may run the
same code); I would expect that the "lock table" statement prevents
concurrent updates.

Any help appreciated.


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