你们有没有发现 py3.6 运算速度变快了

import time
import multiprocessing

def totaltime(ct):
    st = time.time()
    a = 100.33  
    b = 23.33  
    for v in range(ct):
        b = 1 + b
        c = a * b
    print("total time:", time.time()-st)

ct = 25000000

if __name__ == '__main__':
    for i in range(multiprocessing.cpu_count()):
        p = multiprocessing.Process(target=totaltime, args=(ct,))
        p.start()
    for p in multiprocessing.active_children():
        print('Child process name: ' + p.name + ' id: ' + str(p.pid))

这段代码以前要 5s ，现在同一台机器只要 3s 了

import sys, time
stdout = sys.stdout

BAILOUT = 16
MAX_ITERATIONS = 1000

class Iterator:
  def __init__(self):
    print('Rendering...')
    for y in range(-39, 39):
      stdout.write('\n')
      for x in range(-39, 39):
        i = self.mandelbrot(x/40.0, y/40.0)
        
        if i == 0:
          stdout.write('*')
        else:
          stdout.write(' ')
    
  def mandelbrot(self, x, y):
    cr = y - 0.5
    ci = x
    zi = 0.0
    zr = 0.0
    i = 0

    while True:
      i += 1
      temp = zr * zi
      zr2 = zr * zr
      zi2 = zi * zi
      zr = zr2 - zi2 + cr
      zi = temp + temp + ci
 		  
      if zi2 + zr2 > BAILOUT:
        return i
      if i > MAX_ITERATIONS:
        return 0

t = time.time()
Iterator()
print('\nPython Elapsed %.02f' % (time.time() - t))

这段以前要 1.2s ，现在同一台机器只要 0.95s 了

Time

stdout

range

14 条回复 • 2017-01-12 11:09:02 +08:00

PythonAnswer

2017-01-12 03:21:01 +08:00

跟 2.7 比比?

imn1

2017-01-12 08:14:09 +08:00

@PythonAnswer
你不能要求 win10 跟 win xp 比的

mokeyjay

2017-01-12 08:40:23 +08:00 via iPhone

@imn1 你的意思是 2.7 的运算速度更快？→_→

imn1

2017-01-12 08:43:28 +08:00

@mokeyjay
你 @错人了

Ahri

2017-01-12 09:03:38 +08:00

运行 1000 遍取平均值再说

daimoon

2017-01-12 09:24:07 +08:00

python2 -V
Python 2.7.10
python2 t1.py
Child process name: Process-1 id: 697
Child process name: Process-3 id: 699
Child process name: Process-4 id: 700
Child process name: Process-2 id: 698
('total time:', 11.26904296875)
('total time:', 11.378209829330444)
('total time:', 11.391005039215088)
('total time:', 11.501654863357544)

python3 -V
Python 3.5.1
python3 t1.py
Child process name: Process-1 id: 707
Child process name: Process-4 id: 710
Child process name: Process-2 id: 708
Child process name: Process-3 id: 709
total time: 8.77907681465149
total time: 8.84126591682434
total time: 8.84130597114563
total time: 8.845878839492798

dracarysX

2017-01-12 09:29:02 +08:00

有可能是 range 的问题。 python3 优化了 range ，返回的是一个迭代器。

daimoon

2017-01-12 09:29:45 +08:00

python3.6 t1.py
Child process name: Process-2 id: 1191
Child process name: Process-1 id: 1190
Child process name: Process-3 id: 1192
Child process name: Process-4 id: 1193
total time: 6.99714207649231
total time: 7.0236029624938965
total time: 7.036419868469238
total time: 7.042246103286743

daimoon

2017-01-12 09:31:49 +08:00

测试代码改为： xrange 。

python2 t1.py
Child process name: Process-1 id: 1234
Child process name: Process-3 id: 1236
Child process name: Process-4 id: 1237
Child process name: Process-2 id: 1235
('total time:', 6.006057024002075)
('total time:', 6.011800050735474)
('total time:', 6.023754119873047)
('total time:', 6.047795057296753)

daimoon

2017-01-12 09:32:13 +08:00

python3 任重道远啊。

Allenqjy

2017-01-12 09:43:17 +08:00 via iPhone

赶快干死 2.7

gimp

2017-01-12 10:20:42 +08:00

py3 中的 range 就是 py2 中的 xrange

2017-01-12 10:47:35 +08:00

@gimp 不是。 xrange 有长度限制，不能超越机器位长， py3 的 range 没有。

gimp

2017-01-12 11:09:02 +08:00

@fy Thx ，我再去了解一下