Ruby gem released on GitHub at wroclove.rb 2019 by Paweł Pokrywka, two years after his wroclove.rb 2017 talk on performance prediction for distributed applications. Implements the approach shown in that talk — modeling a distributed application and its infrastructure, then simulating performance scenarios — using Petri Nets under the hood. Took three or four attempts to implement and was only feasible in Ruby (earlier Java attempts failed). Ships with an extensive README and is backed by a companion gem providing the Petri-Nets model itself for modeling arbitrary business logic.