So the total for all caches is just the number of object in each connection cache. This means that in theory, with a target size of 400, the system will try hard to make sure that no more than 1600 (persistent) objects are sitting around in memory (400 x 4 ZODB connections).
OK, that explains it. I think that the 'in theory' part is important: I still got a lot more objects cached than 400 * 80 (my current #threads).
On Zope 2.6, the reality is much closer to the theory (thanks to Toby Dickenson for his excellent cache overhaul). Older versions had issues in the cache implementation that made them far less effective than the 2.6 cache :) Brian Lloyd brian@zope.com V.P. Engineering 540.361.1716 Zope Corporation http://www.zope.com