How to Solve a Problem Like Santa Claus
The Santa Claus Problem is a conceptually simple but notoriously tough concurrency problem. For 20 years, the problem has been used to highlight new concurrency features. Polyphonic C# sports an elegant solution using join patterns. I prototyped a version of join patterns for Stackless Python. Rather than hack Stackless Python's C code base, I use PyPy's stackless.py module and greenlets!