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from SimPy.Simulation import *
import random
"""
Machineshop Model
An example showing interrupts and priority queuing.
Scenario:
A workshop has n identical machines. A stream of jobs (enough to keep
the machines busy) arrives. Each machine breaks down
periodically. Repairs are carried out by one repairman. The repairman
has other, less important tasks to perform, too. Once he starts one of
those, he completes it before starting with the machine repair. The
workshop works continously. """
## Model components ------------------------
class Machine(Process):
def __init__(self,name):
Process.__init__(self,name)
myBreaker=Breakdown(self)
activate(myBreaker,myBreaker.breakmachine())
self.partsMade=0
def working(self):
while True:
yield hold,self,timePerPart()
if self.interrupted():
# broken down
parttimeleft=self.interruptLeft
yield request,self,repairman,1
yield hold,self,repairtime
#repaired
yield release,self,repairman
yield hold,self,parttimeleft
# part completed
self.partsMade += 1
else:
#part made
self.partsMade += 1
class Breakdown(Process):
def __init__(self,myMachine):
Process.__init__(self)
self.myMachine=myMachine
def breakmachine(self):
while True:
yield hold,self,timeToFailure()
self.interrupt(self.myMachine)
class OtherJobs(Process):
def __init__(self):
Process.__init__(self)
def doingJobs(self):
while True:
yield request,self,repairman,0
#starts working on jobs
yield hold,self,jobDuration
yield release,self,repairman
def timePerPart():
return random.normalvariate(processingTimeMean,processingTimeSigma)
def timeToFailure():
return random.expovariate(mean)
## Experiment data -------------------------
repairtime=30.0 # minutes
processingTimeMean=10.0 # minutes
processingTimeSigma=2.0
timeToFailureMean = 300.0 # minutes
mean=1/timeToFailureMean # per minute
jobDuration=30 # minutes
nrMachines=10
random.seed(111333555)
weeks = 4 # weeks
simTime = weeks*24*60*7 ## minutes
## Model/Experiment ------------------------------
print 'Machineshop'
initialize()
repairman=Resource(capacity=1,qType=PriorityQ)
m={}
for i in range(nrMachines):
m[i+1]=Machine(name="Machine %s" %(i+1))
activate(m[i+1],m[i+1].working())
oj=OtherJobs()
activate(oj,oj.doingJobs())
simulate(until=simTime) ## minutes
## Analysis/output -------------------------
print "Machineshop results after %s weeks"%weeks
for i in range(nrMachines):
print "Machine %s: %s" %(i+1,m[i+1].partsMade)
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