[Zope] Controlling caching of objects

In Zope 2.6.2 it's quite easy to put an upper limit on the number of objects in memory per thread. But does this mean that Zope won't swap out objects until it reaches that limit? It looks like this: Target # of objects per thread: 20,000 Actual # of objects per thread: ~15,000 Actual # of ghost objects per thread: ~43,000 Were the ghost objects once loaded in memory and then swapped out? If so, why were they swapped out? I find the current system of controlling # of objects in memory per thread to be a bit difficult to use. Most people, I think, would prefer to put an upper limit on the total MB of memory Zope uses instead. Are, what are the cons/pros? Bye, -- Bjorn