Threads, Processes (and Shared Memory)

James Robertson quotes from several interesting pieces on threads, processes, and programming models. I am squarely in the multi-process camp too. I remember my absolute shock about a decade ago when I learned Java (at that time aimed at being a simple web programming language) had a shared-memory with monitors concurrency model.

The key phrase there is "shared-memory". Threads in and of themselves are not the problem. The shared-memory model is the real problem.

With a shared-nothing model then threads take on much more of a "process" feel. Languages like Erlang and Termite implement lightweight shared-nothing processes above the level of the OS. The benefits of sharing lightweight processes within a single address space provide a "best of both worlds" model. Sharing can take place under the abstraction of the language... the runtime benefits of sharing but the developer-time benefits of isolation. Whether an associated process is local, or in another OS process, or on another node, is irrelevant in many respects. Performance, reliability, etc. are still concerns so the distribution problem is not completely abstracted away.