Petri net concurrency March 4, 2011
A petri net is a curious little graphical modeling language for control flow in concurrency. They came up in this talk a few weeks ago: Petri-nets as an Intermediate Representation for Heterogeneous Architectures, but what I found interesting was how I could describe some common concurrency structures using this modeling language.
Here is, for example, the well venerated lock:
The way to interpret the graph is thus: each circle is a “petri dish” (place) that may contain some number of tokens. The square boxes (transitions) are actions that would like to fire, but in order to do so all of the petri dishes feeding into them must have tokens. It’s the sort of representation that you could make into a board game of sorts!