Sorry, I've not run your tests but I'll note that they don't take into account any concurrency or time lost due to conflict error retries. There are many more conflicts when writing to ZEO-backed database in general when there is lots of concurrency because write transactions usually take longer. And even if MVCC bails you out, it still takes time to do the conflict resolution.

There is a set of tests explicitly created to torture test session conflict rates here:

See also:

- C

On May 31, 2006, at 10:58 PM, Sidnei da Silva wrote:

On Wed, May 31, 2006 at 09:59:36AM -0400, Chris McDonough wrote:
| On May 31, 2006, at 9:55 AM, Sidnei da Silva wrote:
| >On Wed, May 31, 2006 at 09:49:49AM -0400, Chris McDonough wrote:
| >| I've done this (at least with FileStorage) and it's
| >| sllllllooooooooowwww. Might be OK for low-traffic sites, but better
| >| to implement a custom session data container that stores stuff in
| >| SQL. I have the beginnings of one of these if you want to see it.
| >
| >Slow for using sessions? Why didn't you use tempstorage then?
| I think I thought it wouldn't have mattered.  The difference between
| using sessions against a local filestorage and one on a ZEO server
| was something like 20X.

So, since I couldn't believe the 20X figure, I wrote a very dumb test
[1] that shows [2] tempstorage to be only slightly slower than
filestorage (roughly 10%) and that adding zeo to the mix makes both of
them about 4X slower, which would be pretty acceptable by my

I'm looking forward for testing tres' memcached stuff tomorrow.

In the meantime, it would be great if someone can run the script on
different boxes and platforms (I've ran it on Windows on a Intel Dual
Core 3.0) to see if there's any difference.


Sidnei da Silva
Enfold Systems      
Fax +1 832 201 8856     Office +1 713 942 2377 Ext 214

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