Yes, each Python Bolt and Spout runs as a separate process. Though, by changing the paralellism hint, you change the number of Python processes spawned per component (e.g. :p 8 = 8 Python processes running the same bolt code).

This is because, under the hood, it all uses ShellBolt/ShellSpout in the Storm layer, which is all process-based. But I actually find this to be the "purer" way to run Storm, anyway. Why deal with threads when you don't need to.

As Joe Armstrong, the creator of Erlang, once said (paraphrasing): "Processes are isolated environments for code where state can't be shared except through explicit messaging; threads are isolated environments where state is directly -- and dangerously -- shared. Why would you want threads when you could have processes?" Ofc, I realize, there are times when threads' lightweightness matters, but it doesn't in our case, and processes are certainly simpler!

As for your question, yes, we are working on async support for pykafka. The async producer is being worked on in this issue: https://github.com/Parsely/pykafka/issues/124 -- feel free to contribute, or even simply +1 as a vote of confidence!