单线程和多线程执行对比—Python多线程编程

单线程和多线程执行对比

本章使用递归求斐波那契、阶乘与累加函数的执行来对比单线程与多线程；

斐波那契、阶乘与累加（mtfacfib.py）：

​

 import threading
 from time import sleep, ctime
 ​
 class MyThread(threading.Thread):
     def __init__(self, func, args, name=''):
         threading.Thread.__init__(self)
         self.name = name
         self.func = func
         self.args = args
 ​
     def getResult(self):
         return self.res
 ​
     def run(self):
         print('starting %s at:%s' % (self.name, ctime()))
         self.res = self.func(*self.args)
         print('%s finished at:%s' % (self.name, ctime()))
 ​
 ​
 def fib(x):
     sleep(0.005)
     if x < 2:
         return 1
     return (fib(x-2) + fib(x-1))
 ​
 def fac(x):
     sleep(0.1)
     if x < 2:
         return 1
     return (x * fac(x-1))
 ​
 def sum(x):
     sleep(0.1)
     if x < 2:
         return 1
     return (x + sum(x-1))
 ​
 funcs = [fib, fac, sum]
 n = 12
 ​
 def main():
     nfuncs = range(len(funcs))
 ​
     print('*** SINGLE THREAD')
     for i in nfuncs:
         print('starting %s at:%s' % (funcs[i].__name__, ctime()))
         print(funcs[i](n))
         print('%s finished at:%s' % (funcs[i].__name__, ctime()))
 ​
     print('\n*** MULTIPLE THREADS')
     threads = []
     for i in nfuncs:
         t = MyThread(funcs[i], (n,), funcs[i].__name__)
         threads.append(t)
 ​
     for i in nfuncs:
         threads[i].start()
 ​
     for i in nfuncs:
         threads[i].join()
         print(threads[i].getResult())
 ​
     print('all Done')
 ​
 if __name__ == '__main__':
     main()

输出结果为：

 E:\Project\Test_Temporary>python mtfacfib.py
 *** SINGLE THREAD
 starting fib at:Fri Jul 27 08:53:18 2018
 233
 fib finished at:Fri Jul 27 08:53:20 2018
 starting fac at:Fri Jul 27 08:53:20 2018
 479001600
 fac finished at:Fri Jul 27 08:53:22 2018
 starting sum at:Fri Jul 27 08:53:22 2018
 78
 sum finished at:Fri Jul 27 08:53:23 2018
 ​
 *** MULTIPLE THREADS
 starting fib at:Fri Jul 27 08:53:23 2018
 starting fac at:Fri Jul 27 08:53:23 2018
 starting sum at:Fri Jul 27 08:53:23 2018
 fac finished at:Fri Jul 27 08:53:24 2018
 sum finished at:Fri Jul 27 08:53:24 2018
 fib finished at:Fri Jul 27 08:53:25 2018
 233
 479001600
 78
 all Done

• 以单线程运行时，只是简单的依次调用每个函数，并在函数执行结束后立即显示相应结果；

• 以多线程模式运行时，不会立即显示结果，而是等线程都结束后再调用 getResult() 方法来最终显示每个函数的返回值。