Can this be taken to mean that:
- the practical maximum number of threads to run your single (non-ZEO) zope instance is {number of zodb connections in pool} else you risk deadlock
No, there should be more connections than threads, just as in the original configuration.
if yes, would upping the number of ZODB connections effectively raise the ceiling - e.g. 12 ZODB connections -> 12 threads should perform properly ? Is increasing the number of ZODB cx's possible, let alone advisable? (why the default of 7 - not 6 or 8?)
More concretely, is there any good way to increase the request-handling capacity of a standalone instance, beyond the limits imposed by the defaults, without deploying ZEO?
Trying to squeeze a single instance that way is fraught with problems, and not just the experimentation needed to come up with sane values for threads, connections, and then connection cache sized to avoid memory contention. A single Zope process also means you are running one Python process with one global interpreter lock. It's just a bad situation to base a production site on. Use ZEO and set up additional clients as needed, anything else is hackish and error-prone. jens