为什么Cython Decorator版本比Cython Pyx版本慢？

Question

I am trying all sorts of ways to write the factorial function in Cython. First I tried the pyx file version in iPython Notebook.

%%file pyxfact.pyx
cdef long pyxfact(long n):
    if n <=0:
        return 1
    else:
        return n * pyxfact(n-1)

def fact(long n):
    return pyxfact(n)

Then I tried the same, as least I think so, in Cython decorator, like this:

%%file cydecofact.py
import cython

@cython.cfunc # equivalent to cdef, while @cython.ccall is equivalent to cpdef
@cython.returns(cython.long)
@cython.locals(n=cython.long)
def deco_fact(n):
    if n <=0:
        return 1
    else:
        return n * deco_fact(n-1)

@cython.locals(n=cython.long)
def fact(n):
    return deco_fact(n)

To my surprise, the two versions have a huge run time difference:

%timeit -n 10000 pyxfact.fact(10)
%timeit -n 10000 cydecofact.fact(10)

10000 loops, best of 3: 219 ns per loop
10000 loops, best of 3: 2 µs per loop

Answer 1

You need a @cython.compile to actually compile the code. However, it looks like neither cython.cfunc nor recursion is supported for @cython.compile .