Python extension modules written in C are faster than the equivalent programs written in pure Python. How do these extension modules compare (speed wise) to programs written in pure C? Are programs written in pure C even faster than the equivalent Python extension module?
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Maybe you should consider Cython if you think about writing extensions/modules/...hochl– hochl2012-02-19 01:46:34 +00:00Commented Feb 19, 2012 at 1:46
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@hochl -- Isn't Cython just regular Python? As opposed to Jython or IronPython?mau5padd– mau5padd2012-02-19 05:19:50 +00:00Commented Feb 19, 2012 at 5:19
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Cython is like Python code that can be compiled for speedup. In most situations you gain a speedup between 20 to 50 times. See cython.org.hochl– hochl2012-02-19 12:22:03 +00:00Commented Feb 19, 2012 at 12:22
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2 Answers
How do these extension modules compare (speed wise) to programs written in pure C?
They are slightly slower due to the translation between Python data structures -> C types. Disregarding this translation the actual C code runs at exactly the same speed as a regular C function would.
Are programs written in pure C even faster than the equivalent Python extension module?
C programs (written entirely in C) can be faster than Python programs using the C extension modules. If the C program and the extension module are written with the same level of complexity, coder skill, algorithmic complexity, etc., the C program will win every time. However, if you're not a C guru and you're competing with a highly optimized Python C extension Python could be faster.
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Being a Python extension doesn't affect the execution speed of a piece of code, except insofar as the Python invoking it is slower than the equivalent C would be, and the compiler is less able to aggressively unroll and inline code which crosses the C/Python boundary.
That is to say, if you just have Python code call a C function, and then you do all your work in that function, the only performance difference is going to be the amount of time you spent before getting into the C side of things. From that point on, it is native C.
