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a87150
V2EX  ›  Python

你们有没有发现 py3.6 运算速度变快了

  •  
  •   a87150 · 2017-01-12 02:53:39 +08:00 · 5296 次点击
    这是一个创建于 2858 天前的主题,其中的信息可能已经有所发展或是发生改变。
    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

    14 条回复    2017-01-12 11:09:02 +08:00
    PythonAnswer
        1
    PythonAnswer  
       2017-01-12 03:21:01 +08:00
    跟 2.7 比比?
    imn1
        2
    imn1  
       2017-01-12 08:14:09 +08:00
    @PythonAnswer
    你不能要求 win10 跟 win xp 比的
    mokeyjay
        3
    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
        4
    imn1  
       2017-01-12 08:43:28 +08:00
    @mokeyjay
    你 @错人了
    Ahri
        5
    Ahri  
       2017-01-12 09:03:38 +08:00
    运行 1000 遍取平均值再说
    daimoon
        6
    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
        7
    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
        8
    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
        9
    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
        10
    daimoon  
       2017-01-12 09:32:13 +08:00
    python3 任重道远啊。
    Allenqjy
        11
    Allenqjy  
       2017-01-12 09:43:17 +08:00 via iPhone
    赶快干死 2.7
    gimp
        12
    gimp  
       2017-01-12 10:20:42 +08:00
    py3 中的 range 就是 py2 中的 xrange
    fy
        13
    fy  
       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
        14
    gimp  
       2017-01-12 11:09:02 +08:00
    @fy Thx ,我再去了解一下
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