[Python] Python 加速对比

// Dll1.h
#ifndef PCH_H
#define PCH_H

#ifdef __cplusplus
extern "C" {
#endif
    __declspec(dllexport) int fib(int n);
    __declspec(dllexport) int testfib(int value, int n);
#ifdef __cplusplus
}
#endif
#endif //PCH_H

// Dll1.c
#include "pch.h"

int fib(int n)
{
    if (n <= 2)
        return 1;
    return fib(n - 1) + fib(n - 2);
}

int testfib(int value, int n)
{
    int t = 0;
    for (int i = 1; i < n + 1; i++)
    	// 加个条件判断，防止固定语句被编译器优化掉
        if (i % 2)
            t = fib(value + (i % 2));
        else
            t = fib(value + (i % 3));
    return t;
}

from ctypes import *
import time

def fib(n):
    if n <= 2:
        return 1
    return fib(n - 1) + fib(n - 2)

def testfib(value, n):
    t = 0
    for i in range(1, n + 1):
        if i % 2:
            t = fib(value + (i % 2))
        else:
            t = fib(value + (i % 3))
    return t
    
path = "./Dll1.dll"
num = 15
repeat = 500000

dll = cdll.LoadLibrary(path)
dll.fib.retype = c_int
dll.testfib.retype = c_int

# 调用 C 函数
st = time.time() * 1000
t = dll.testfib(num, repeat)
print("dll.testfib(): %.3f ms, final: %d" % (time.time() * 1000 - st, t))

# 循环调用 C 函数 fib()，实现与 testlib() 相同逻辑
st = time.time() * 1000
for i in range(1, repeat + 1):
    if i % 2:
        t = dll.fib(num + (i % 2))
    else:
        t = dll.fib(num + (i % 3))
print("dll.fib(): %.3f ms, final: %d" % (time.time() * 1000 - st, t))

# 纯 Python
st = time.time() * 1000
t = testfib(num, repeat)
print("Python: %.3f ms, final: %d" % (time.time() * 1000 - st, t))

%%cython -f 
import time
cpdef int fib(int n):
    if n <= 2:
        return 1
    return fib(n - 1) + fib(n - 2)

cpdef int testfib(int value, int n):
    cdef int t = 0
    cdef int i = 0
    for i in range(1, n + 1):
        # 加个条件判断，防止固定语句被优化掉
        if i % 2:
            t = fib(value + (i % 2))
        else:
            t = fib(value + (i % 3))
    return t
    
st = time.time() * 1000    
t = testfib(15, 500000)
print("cython: %.3f ms, final: %d" % (time.time() * 1000 - st, t))

• Windows 7 x64
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• 内存 16G
• VS2019