[ZODB-Dev] ZODB open/close profilings

[Christian Reis]

On Tue, Dec 10, 2002 at 02:17:15PM -0500, Jeremy Hylton wrote:
>   GW> * but the real culprit is FileStorage._sane(), which takes 28
>   GW>     sec of the ~48 sec total opening time
> 
> I've never thought about the cost of _sane(), so this is a great
> clue.  I think part of the problem is that you don't use undo() enough
> <wink>.  The code scans the entire data.fs backwards, looking for a
> transaction marked with 'u' for undo.  Since you never do an undo, it
> reads the whole file backwards after reading it forwards.  Yikes.

True, we have:

    1   28.621   28.621   41.913   41.913 
        /www/python/lib/python2.2/site-packages/ZODB/FileStorage.py:347(_sane)

I wonder if we can cache the fact that no undos were found on the
forward read and avoid the backwards read if true? We never use undo()
either :-)

Take care,
--
Christian Reis, Senior Engineer, Async Open Source, Brazil.
http://async.com.br/~kiko/ | [+55 16] 261 2331 | NMFL