Bank Renege


  • Resources
  • Event operators

A counter with a random service time and customers who renege.

This example models a bank counter and customers arriving at random times. Each customer has a certain patience. It 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.

using SimJulia
using Distributions

const RANDOM_SEED = 150
const NEW_CUSTOMERS = 5  # Total number of customers
const INTERVAL_CUSTOMERS = 10.0  # Generate new customers roughly every x seconds
const MIN_PATIENCE = 1.0  # Min. customer patience
const MAX_PATIENCE = 3.0  # Max. customer patience

function source(env::Environment, number::Int, interval::Float64, counter::Resource)
  d = Exponential(interval)
  for i in 1:number
    Process(env, customer, "Customer$i", counter, 12.0)
    yield(Timeout(env, rand(d)))

function customer(env::Environment, name::ASCIIString, counter::Resource, time_in_bank::Float64)
  arrive = now(env)
  println("$arrive $name: Here I am")
  req = Request(counter)
  patience = rand(Uniform(MIN_PATIENCE, MAX_PATIENCE))
  result = yield(req | Timeout(env, patience))
  wait = now(env) - arrive
  if in(req, keys(result))
    println("$(now(env)) $name: Waited $wait")
    yield(Timeout(env, rand(Exponential(time_in_bank))))
    println("$(now(env)) $name: Finished")
    println("$(now(env)) $name: RENEGED after $wait")
    cancel(counter, req)

# Setup and start the simulation
println("Bank renege")
env = Environment()

# Start processes and run
counter = Resource(env, 1)
Process(env, source, NEW_CUSTOMERS, INTERVAL_CUSTOMERS, counter)

The simulation’s output:

Bank renege
0.0 Customer1: Here I am
0.0 Customer1: Waited 0.0
4.435484832567573 Customer1: Finished
21.013085103081753 Customer2: Here I am
21.013085103081753 Customer2: Waited 0.0
23.097746900916643 Customer3: Here I am
23.91170855317896 Customer2: Finished
23.91170855317896 Customer3: Waited 0.8139616522623179
30.113622311091923 Customer4: Here I am
30.621135918022613 Customer5: Here I am
32.43509581615485 Customer5: RENEGED after 1.8139598981322358
32.63868913452709 Customer3: Finished
32.63868913452709 Customer4: Waited 2.525066823435168
35.25594434892944 Customer4: Finished