I would say the most natural is STM - you don't need to change much, just wrap your concurrent, shared memory accessing code in a STM transaction, be careful wi

I would say the most natural is STM - you don't need to change much, just wrap your concurrent, shared memory accessing code in a STM transaction, be careful with IO (or use a language which prohibits IO in a STM block like Haskell) and you are done. Actors are pretty nice when it comes to distributed services, and Erlang/OTP is pretty much uncontested here. Threads with manual locking are only useful when speed is really important, but this is somewhat of a moot point when it comes to concurrency. Both STM and Actors perform slower (starvation, message copying overhead). Here [0] is a nice, in-depth discussion about some of the different approaches to concurrency. [0] https://plus.google.com/109566665911385859313/posts/FAmNTExSLtz https://plus.google.com/109566665911385859313/posts/FAmNTExS...