Where you were already using external queues, threads shouldn't have been an issue: just have multiple processes going (one for each core). Or use the processing package if you want more "threadlike" control.

It is unfortunate that you have to know that kind of thing a priori.

"Oh, look, a nice, built-in threading module."

Yes, BUT...

EDIT: I just re-read the way you wrote the "threading" comment and realized you probably weren't talking about it in the same context. Amazing what a word or two can do to understanding.