"Any locked (or lock-free) pointer queue with the right ownership semantics will give you what ZMQ does within a threaded program." OK, now I think you're trol

"Any locked (or lock-free) pointer queue with the right ownership semantics will give you what ZMQ does within a threaded program." OK, now I think you're trolling, perhaps by cutting and pasting from random technical manuals. What you said there makes no sense at all. Could you paste some example code please? "A coroutine library will get you even more flexibility if you just want to setup pipelines." Now I know you're trolling. Coroutines are completely useless for real concurrency like decoding audio and video in the background simultaneously - because only one coroutine can be executing at the same time. "If you want greater scalability, there are lots of non-blocking I/O event libraries (libuv/libevent/boost asio). None of these solutions involve moving to a message passing model." What if I don't really care about I/O? What if I have a small program that needs to use multiple threads on multiple cores to efficiently search a large problem space while doing video decoding in the background and having a responsive UI? I must just link to Boost? Er, no thanks. "I'm not discrediting that operating between threads is a handy addition to ZMQ, but using it for communication between threads seems like a lot of work (moving to that message passing model) if you never intend to leave one process." Compared to getting synchronization right, optimizing critical sections, debugging random failures under load, it's trivial. "I do happen to like messaging, but when your data becomes complex it's a right dog...you're now in the world of protocol design." I'm going to assume that you're still in school or not actually a programmer. ZeroMQ is used by AT&T, Cisco, EA, Los Alamos Labs, NASA, Weta Digital, Zynga, Spotify, Samsung Electronics, Microsoft, and CERN (I grabbed this list from its front page). CERN just published a report in which it evaluated ZeroMQ for a custom middleware solutions running 4000 server processes communicating with 80 000 devices for a total of 2 000 000 I/O points that could be queried. It aced the requirements. Erlang has used message passing for decades in the telecoms industry which has enormously complex data and unique realtime, distributed requirements. Protocol design is easy. Main thread creates child. Child loads video and reports its ready. Main thread sends START. Child thread receives START and starts. Child thread reports DONE when done. Was that so hard?