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这个python代码有什么问题吗?为什么它比ruby运行得那么慢?

fibonacci performance ruby python

rapadura · 技术社区 · 15 年前

我有兴趣比较Rubyspeed和python,所以我采用了最简单的递归计算,即打印fibonacci亮片。

这是python代码

#!/usr/bin/python2.7                       
def fib(n):
    if n == 0: 
        return 0
    elif n == 1:
        return 1 
    else:
        return fib(n-1)+fib(n-2)

i = 0
while i < 35:
    print fib(i)
    i = i + 1

这是红宝石代码

#!/usr/bin/ruby

def fib(n)
    if n == 0
        return 0
    elsif n == 1
        return 1
    else
        fib(n-1)+fib(n-2)
    end
end 

i = 0 
while (i < 35)
    puts fib(i)
    i = i + 1 
end

在几次运行中,时间报告此平均值

real    0m4.782s 
user    0m4.763s 
sys     0m0.010s

那是红宝石,现在python2.7给出了

real    0m11.605s
user    0m11.563s
sys     0m0.013s

这笔交易是什么?

5 回复 | 直到 15 年前

dcolish 15 年前

this article

Sven Marnach 15 年前

a, b = 1, 1
for i in range(35):
    a, b = b, a+b
print b

Rafe Kettler 15 年前

def fibo_generator(n):
    # gets Fibonacci numbers up to nth number using a generator
    a, b = 0, 1
    for _ in range(n):
        yield a
        a, b = b, a + b

for f in fibo_generator(35):
    print f

Jochen Ritzel 15 年前

google for "language shootout"

Python and Ruby

jfs 15 年前

Python2.7
9.67 user 0.09 system 0:09.78 elapsed 99%CPU (0avgtext+0avgdata 16560maxresident)k
0inputs+0outputs (0major+1169minor)pagefaults 0swaps

ruby 1.8.7 (2010-06-23 patchlevel 299) [x86_64-linux]
28.37 user 0.35 system 0:28.78 elapsed 99% CPU (0avgtext+0avgdata 9200maxresident)k
1896inputs+0outputs (9major+656minor)pagefaults 0swaps

ruby 1.9.2p0 (2010-08-18 revision 29036) [x86_64-linux]
6.21 user 0.08 system 0:06.36 elapsed 98% CPU (0avgtext+0avgdata 14160maxresident)k
4416inputs+0outputs (16major+953minor)pagefaults 0swaps

2.4.6 took 10.30 seconds

2.5.5 took 9.93 seconds

2.6.6 took 9.22 seconds

2.7   took 9.35 seconds

3.0.1 took 11.67 seconds

3.1.2 took 11.35 seconds

3.2a3+ (py3k:85895, Oct 29 2010, 01:41:57) 
[GCC 4.4.5] took 13.09 seconds

2.5.2 (77963, Oct 15 2010, 02:00:43)
[PyPy 1.3.0] took 21.26 seconds

2.5.1 (Release_2_5_1:6813, Sep 26 2009, 13:47:54) 
[OpenJDK 64-Bit Server VM (Sun Microsystems Inc.)] took 8.81 seconds

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