"Python core Programming" 18. Multithreaded Programming (III)

18.6 using the Threading module

#!/usr/bin/env python#-*-coding:utf-8-*-"""derive a child from the thread class and create an instance of the subclass"""ImportThreading fromTimeImportSleep, Ctimeloops= (4, 2)classMyThread (Threading. Thread):"""1. Subclass Thread Class 2. To call the constructor of the base class first, explicitly overwrite 3. Redefine the run () function"""    def __init__(Self, func, args, name="'): Super (MyThread, self).__init__() Self.name=name Self.func=func Self.args=argsdefRun (self): Self.func (*Self.args)defLoop (Nloop, nsec):Print 'Start Loop', Nloop,'At :', CTime () sleep (nsec)Print 'Loop', Nloop,'Done at :', CTime ()defMain ():Print 'starting at:', CTime () Threads=[] Nloops=Range (len (loops)) forIinchNloops:t= MyThread (Loop, (I, loops[i]), loop.__name__)#to create an instance of a subclassthreads.append (t) forIinchNloops:threads[i].start () forIinchNloops:threads[i].join ()Print 'All do at :', CTime ()if __name__=='__main__': Main ()

18.7MyThread sub-class

#!/usr/bin/env python#-*-coding:utf-8-*-"""1. Separate subclasses to make the subclasses of thread more generic. 2. Add the GetResult () function to return the running result of the function. """ImportThreading fromTimeImportCTimeclassMyThread (Threading. Thread):def __init__(Self, func, args, name="'): Threading. Thread.__init__(self) self.name=name Self.func=func Self.args=argsdefGetResult (self):returnSelf.resdefRun (self):Print 'starting', Self.name,'At :', CTime () self.res=Apply (Self.func, Self.args)PrintSelf.name,'finished at:', CTime ()

18.8 Fibonacci, factorial, summation and

#!/usr/bin/env python#-*-coding:utf-8-*- fromMyThreadImportMyThread fromTimeImportCTime, Sleepdeffib (x):"""To find the sum of Fibonacci sequences"""Sleep (0.005)    ifX < 2:        return1returnFIB (x-2) + fib (x-1)defFAC (x):"""find factorial"""Sleep (0.1)    ifX < 2:        return1returnX * FAC (x-1)defsum_ (x):"""natural number accumulation and"""Sleep (0.1)    ifX < 2:        return1returnx + sum_ (x-1) Funcs= [FIB, FAC, SUM_]#put three functions in a listn = 12defMain (): Nfuncs= Range (len (funcs))#Nfuncs = Range (3)    Print '* * Single THREAD'  #single-threaded calculation of three functions     forIinchNfuncs:Print 'Staring', Funcs[i].__name__,'CTX', CTime ()#Print out function name, start run time        PrintFuncs[i] (N)#Print Calculation Results        PrintFuncs[i].__name__,'finished at:', CTime ()#Print out function name, end run time    Print '\n*** multiple THREADS'  #Multi-threaded computation of three functionsThreads = []     forIinchNfuncs:t= MyThread (Funcs[i], (n,), Funcs[i].__name__)#instantiation of three Mythread objectsThreads.append (t)#place three objects in a list     forIinchNfuncs:threads[i].start ()#Start Three Threads     forIinchNfuncs:threads[i].join ()#join () waits for the thread to end or time out, which allows the main thread to wait for threads to end        PrintThreads[i].getresult ()#the GetResult () method of the calling object    Print ' All done'if __name__=='__main__':#runs the script independently, that is, the main () function is called when this script is run directlyMain ()

18.9 Producer-Consumer issues

#!/usr/bin/env python#-*-Coding:utf8-*- fromRandomImportRandint#Randint randomly for production and consumption fromTimeImportSleep fromQueueImportQueue fromMyThreadImportMyThreaddefWriteq (queue):Print 'producing object for Q ...', Queue.put ('XXX', 1)#Put the xxx object into the queue and wait for space in the queue    Print "size Now", Queue.qsize ()#return Queue SizedefREADQ (Queue): Val= Queue.get (1)#fetching an object from the queue (consumption)    Print 'consumed Object form Q ... size now', Queue.qsize ()#return Queue Sizedefwriter (queue, loops):"""put an object in the queue one at a time, wait for a while, and then do the same thing for a given number of times"""     forIinchRange (Loops): Writeq (queue)#call Writeq, put in an objectSleep (Randint (1, 3))#random sleep 1-3 secondsdefReader (queue, loops):"""Take an object out of the queue one at a time, wait a while, and do the same thing for a given number of times"""     forIinchRange (Loops): READQ (queue) sleep (Randint (2, 5))#sleep longer than write, so that reader can get data when fetching dataFuncs=[Writer, Reader]nfuncs=Range (len (funcs))defMain (): Nloops= Randint (2, 5) Q= Queue (32)#create an object of size 32, and a Q bindingThreads= []     forIinchNfuncs:t= MyThread (Funcs[i], (Q, Nloops), Funcs[i].__name__)#Instantiate writer, reader these two objectsThreads.append (t)#put in an empty list     forIinchNfuncs:threads[i].start ()#Start Thread     forIinchNfuncs:threads[i].join ()#join () waits for the thread to end or time out, which allows the main thread to wait for threads to end    Print ' All done'if __name__=='__main__':#Run scripts independentlyMain ()

Python core programming 18. Multithreaded Programming (iii)