What is the "Hello World" of concurrent programs?

Question

I'm looking for some canonical, simple concurrency problems, suitable for demonstrating usage of a library for concurrent computations I'm working on.

To clarify what I mean by "concurrency": I'm interested in algorithms that utilize non-deterministic communicating processes, not in e.g. making algorithms like quicksort run faster by spreading the work over multiple processors. This is how I'm using the term.

I know about the Dining Philosophers Problem, and that would be acceptable, but I wonder whether there are any more convincing but equally simple problems.

Answer 1

Producer-Consumer problem.