Here is a handy implementation of process pool I wrote a few days ago. All workers are created in pool and are running in daemonic mode, reading and executing ProcessTasks, which is made up using any python callable together with callback and exception callback definition.
The process pool is using two queues: first for tasks to be processed and second holding task results for callbacks. It could be executed in daemon mode too, processing results in a separate thread. Once you decide the job is done, you need to call ProcessPool::finalize (or ProcessPool::processAllResults), which is sending dummy assassins (in fact just a True value) to the workers (so they could return from their run method), terminating them once they are not alive any more and closing tasks and results queues.
Blah, blah, blah... Code that was published below was kinda buggy. Error-free version can be found here.
