- Resources: Resource
- Condition events
A counter with a random service time and customers who renege. Based on the program bank08.py from TheBank tutorial of SimPy 2. (KGM)
This example models a bank counter and customers arriving at random times. Each customer has a certain patience. She waits to get to the counter until she’s at the end of her tether. If she gets to the counter, she uses it for a while before releasing it.
New customers are created by the
source process every few time steps.
""" Bank renege example Covers: - Resources: Resource - Condition events Scenario: A counter with a random service time and customers who renege. Based on the program bank08.py from TheBank tutorial of SimPy 2. (KGM) """ import random import simpy RANDOM_SEED = 42 NEW_CUSTOMERS = 5 # Total number of customers INTERVAL_CUSTOMERS = 10.0 # Generate new customers roughly every x seconds MIN_PATIENCE = 1 # Min. customer patience MAX_PATIENCE = 3 # Max. customer patience def source(env, number, interval, counter): """Source generates customers randomly""" for i in range(number): c = customer(env, 'Customer%02d' % i, counter, time_in_bank=12.0) env.process(c) t = random.expovariate(1.0 / interval) yield env.timeout(t) def customer(env, name, counter, time_in_bank): """Customer arrives, is served and leaves.""" arrive = env.now print('%7.4f %s: Here I am' % (arrive, name)) with counter.request() as req: patience = random.uniform(MIN_PATIENCE, MAX_PATIENCE) # Wait for the counter or abort at the end of our tether results = yield req | env.timeout(patience) wait = env.now - arrive if req in results: # We got to the counter print('%7.4f %s: Waited %6.3f' % (env.now, name, wait)) tib = random.expovariate(1.0 / time_in_bank) yield env.timeout(tib) print('%7.4f %s: Finished' % (env.now, name)) else: # We reneged print('%7.4f %s: RENEGED after %6.3f' % (env.now, name, wait)) # Setup and start the simulation print('Bank renege') random.seed(RANDOM_SEED) env = simpy.Environment() # Start processes and run counter = simpy.Resource(env, capacity=1) env.process(source(env, NEW_CUSTOMERS, INTERVAL_CUSTOMERS, counter)) env.run()
The simulation’s output:
Bank renege 0.0000 Customer00: Here I am 0.0000 Customer00: Waited 0.000 3.8595 Customer00: Finished 10.2006 Customer01: Here I am 10.2006 Customer01: Waited 0.000 12.7265 Customer02: Here I am 13.9003 Customer02: RENEGED after 1.174 23.7507 Customer01: Finished 34.9993 Customer03: Here I am 34.9993 Customer03: Waited 0.000 37.9599 Customer03: Finished 40.4798 Customer04: Here I am 40.4798 Customer04: Waited 0.000 43.1401 Customer04: Finished