[ZODB-Dev] Re: [Zope-dev] tempstorage to ZEO?

[Chris McDonough]

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:

http://cvs.zope.org/Packages/SessionRig/

See also:

http://www.plope.com/Members/dunny/conflicts/view

- 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
> standards.
>
> 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.
>
> [1] http://awkly.org/files/zeo-bench/bench.py
> [2] http://awkly.org/files/zeo-bench/bench_results.txt
>
> -- 
> Sidnei da Silva
> Enfold Systems                http://enfoldsystems.com
> Fax +1 832 201 8856     Office +1 713 942 2377 Ext 214
>