Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From: Mark Lawrence <breamoreboy@yahoo.co.uk>
Newsgroups: comp.lang.python
Subject: Re: Pyhon 2.x or 3.x, which is faster?
Date: Tue, 8 Mar 2016 20:44:17 +0000
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On 08/03/2016 19:15, BartC wrote:
> On 08/03/2016 16:09, Mark Lawrence wrote:
>> On 08/03/2016 11:09, BartC wrote:
>>> On 08/03/2016 02:45, Mark Lawrence wrote:
>>>> On 08/03/2016 01:47, BartC wrote:
>>>
>>>>> The Python timing for that file is around 20 seconds, time enough to
>>>>> read 10000 copies from the disk.
>>>>>
>>>>> And a C program reads /and decodes/ the same file from the same
>>>>> disk in
>>>>> between 0.1 and 0.2 seconds.
>>>>>
>>>>
>>>> So how much of that time is Python startup time, compared to C which is
>>>> effectively zero?
>>>
>>> Virtually zero as well.
>>
>> Nonsense.
>>
>>>
>>> That's if by start-up time you mean how long between invoking Python
>>> with the name of the main module, executing all the imports and defs in
>>> the main and imported modules, until it starts properly executing code.
>>>
>>> In the jpeg test, perhaps 50ms. And it would not depend on the size of
>>> the input since the start-up routines won't know that.
>>
>> How did you obtain that figure?
>
> By printing a message followed by exit(0) just before the program was
> about to start doing its thing.
>
> Then I timed that using:
>
>    $time python program.py
>
> in Linux.
>
> But this was hardly necessary as it was so obvious: it takes 150ms to
> process a 300-pixel image, 20 seconds for a 2Mpixel one, and (I have to
> switch to PyPy here as I've never had time to hang about for it) 180
> seconds for 80Mpixel file.
>
> Surely the start-up time would be the same no matter what the input.
>

Unless all of the background jobs are kicking in when you're testing.  I 
assume that you do take such factors into account, by repeating your 
tests and taking an average, or perhaps even a worst case figure.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence