SimpyLens is a low-intrusion toolkit for SimPy model visualization, debugging, and runtime inspection. It helps developers understand queueing behavior, resource contention, and process flow in real time without rewriting simulation business logic.
assets/pottery_factory.gif shows the full SimpyLens interface for discrete-event simulation debugging: runtime controls, process flow, resource movement, and live inspection.
It is useful for users searching for a SimPy visual debugger, queueing simulation viewer, or simulation runtime inspection tool.
assets/manual_layout.gif demonstrates manual resource positioning so teams can present and analyze process flow with a clearer mental model.
This is especially relevant for simulation demos, teaching, and operations reviews where layout readability matters.
- Real-time visualization for SimPy resources and process interactions.
- Runtime controls for play, step, pause, reset, and speed.
- Breakpoints with expression/callable conditions and edge modes.
- Structured logs for simulation, step lifecycle, resources, and breakpoints.
- Headless mode for tests and CI.
- Optional metrics collection with read-only resource metrics.
pip install simpylensimport simpy
import simpylens
def model(env):
server = simpy.Resource(env, capacity=1)
def customer():
with server.request() as req:
yield req
yield env.timeout(3)
env.process(customer())
lens = simpylens.Lens(model=model, gui=True, seed=42)
lens.show()Examples are in examples/ and grouped by origin.
Adapted from official simpy examples/tutorial lineage:
examples/bank_renege.pyexamples/gas_station_refueling.py
Original SimpyLens examples:
examples/pottery_factory.pyexamples/wafer_fabrication.py
Yes. SimpyLens provides breakpoint-based debugging, structured event logs, and step-by-step runtime inspection for SimPy simulations.
Yes. SimpyLens visualizes Resource, Container, and Store families, including queue/load behavior and process flow.
Yes. Use Lens(gui=False) to run simulations and assertions in tests or CI pipelines.
No. SimpyLens is designed for low-intrusion integration with your existing SimPy setup function.
Contributions are welcome.
Suggested workflow:
- Fork the repository.
- Create a feature branch.
- Add or update tests and examples.
- Submit a pull request with a clear change description.