""" bank24. BCC system with several counters """
from SimPy.Simulation import *
from random import expovariate,seed
## Model components ------------------------
class Source(Process):
""" Source generates customers randomly """
def generate(self,number,meanTBA,resource):
for i in range(number):
c = Customer(name = "Customer%02d"%(i,))
activate(c,c.visit(b=resource))
t = expovariate(1.0/meanTBA)
yield hold,self,t
class Customer(Process):
""" Customer arrives, is served and leaves """
numBalking = 0
def visit(self,b):
arrive = now()
print "%8.4f %s: Here I am "%(now(),self.name)
if len(b.waitQ) < maxInQueue: # the test
yield request,self,b
wait = now()-arrive
print "%8.4f %s: Wait %6.3f"%(now(),self.name,wait)
tib = expovariate(1.0/timeInBank)
yield hold,self,tib
yield release,self,b
print "%8.4f %s: Finished "%(now(),self.name)
else:
Customer.numBalking += 1
print "%8.4f %s: BALKING "%(now(),self.name)
## Experiment data -------------------------------
timeInBank = 12.0 # mean, minutes
ARRint = 10.0 # mean interarrival time, minutes
numServers = 1 # servers
maxInSystem = 2 # customers
maxInQueue = maxInSystem - numServers
maxNumber = 8
maxTime = 4000.0 # minutes
theseed = 12345
## Model/Experiment ------------------------------
seed(theseed)
k = Resource(capacity=numServers,
name="Counter",unitName="Clerk")
initialize()
s = Source('Source')
activate(s, s.generate(number=maxNumber,meanTBA=ARRint,
resource=k),at=0.0)
simulate(until=maxTime)
## Results -----------------------------------------
nb = float(Customer.numBalking)
print "balking rate is %8.4f per minute"%(nb/now())
|