Hi,
When running a tg2 app with "paster serve", I was expecting controller objects to be instantiated once per worker thread.
I've even been surprised by them being instantiated more than once per process.
But it's not as bad as it looks.
However, when I add logging to BaseController.__init__, it seems that the full hierarchy of controller objects is instantiated once per request. E.g. when I exercised my app with ab -c 100 -n 1000 (100 concurrent clients making 1000 requests, total) the controller objects were instantiated 1000 times...
No. The *root* controller is instantiated as often as that. But clearly all sub-controllers ar class-attributes, thus they aren't instantiated more than once per process.
Is that wierd? Certainly. If you insist, just make the root-controller a singleton. But I doubt the instantiation overhead of that one object really matters (unless the __init__-method does soemthing, which none of our controllers does, as they are not supposed to hold any state whatsoever).
What you won't get under no circumstances though is a per-thread- instantiation, unless you code it yourself of course.
Is that the expected behaviour with paster serve? Does anyone know if mod_wsgi, for example, is different?
No, it isn't. It takes the same WSGI app entry point. Whatever happens with the controllers is subject to the routes/object-dispatch code.
The reason I ask is that I need (non-DB) connections in my controller methods which are fairly expensive to create. If controller instantiation is once per thread, I'll need to create a connection pool, populate it at startup and manage it over time; is there a best practice for this?
I don't fully understand what you are after here. Do you actially want a pool of connections, per thread? Then you need to manage that yourself, yes.
But it's easy enough. Just create a threadlocal attribute, either at module-level, or controller-level, or wherever you like. When it's not set in the current thread, instantiate a connection. Use the existing one otherwise.
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