From the StackOverflow post (it was recommended I move this):

So, I'm working on a game engine, and I've made pretty good progress. However, my engine is single-threaded, and the advantages of splitting updating and rendering into separate threads sounds like a very good idea.

How should I do this? Single threaded game engines are (conceptually) very easy to make, you have a loop where you update -> render -> sleep -> repeat. However, I can't think of a good way to break updating and rendering apart, especially if I change their update rates (say I go through the update loop 25x a second, and have 60fps for rendering) - what if I begin updating halfway through a render loop, or vice versa?