[Seaside] WARegistry performance

[Lukas Renggli]

> We've tested our seaside (2.8) application with ab [1] and found that
> the performance decreases with repeated runs of the benchmark.
> Ab creates a new session for every request, so we've looked into the
> session handling code and found that WARegistry spends O(n)
> time with housekeeping for every new session, where n is the number of
> registered sessions. This means that creating n sessions rapidly
> takes O(n^2) time.

Is the creation of dozens of new session a realistic benchmark for a
typical Seaside application? Do you have a practical use-case where
this actually matters?

I don't think so. The creation of new sessions is a "relatively" rare
event compared to all the requests coming in. Furthermore, the
registry-bookkeeping causing an iteration over all active session only
happens every 10th time, so normally users should not notice this
anyway.

Cheers,
Lukas

-- 
Lukas Renggli
http://www.lukas-renggli.ch