[Python-Dev] Python startup time

[Michel Desmoulin]

Le 23/07/2017 à 19:36, Brett Cannon a écrit :
> 
> 
> On Sun, Jul 23, 2017, 00:53 Michel Desmoulin, <desmoulinmichel at gmail.com
> <mailto:desmoulinmichel at gmail.com>> wrote:
> 
> 
> 
>     > Optimizing startup time is incredibly valuable,
> 
>     I've been reading that from the beginning of this thread but I've been
>     using python since the 2.4 and I never felt the burden of the
>     startup time.
> 
>     I'm guessing a lot of people are like me, they just don't express them
>     self because "better startup time can't be bad so let's not put a
>     barrier on this".
> 
>     I'm not against it, but since the necessity of a faster Python in
>     general has been a debate for years and is only finally catching up with
>     the work of Victor Stinner, can somebody explain me the deal with start
>     up time ?
> 
>     I understand where it can improve your lives. I just don't get why it's
>     suddenly such an explosion of expectations and needs.
> 
> 
> It's actually always been something we have tried to improve, it just
> comes in waves. For instance we occasionally re-examine what modules get
> pulled in during startup. Importlib was optimized to help with startup.
> This just happens to be the latest round of trying to improve the situation.
> 
> As for why we care, every command-line app wants to at least appear
> faster if not be faster because just getting to the point of being able
> to e.g. print a version number is dominated by Python and app start-up.


Fair enought.

> And this is not guessing; I work with a team that puts out a command
> line app and one of the biggest complaints they get is the startup time.

This I don't get. When I run any command line utility in python (grin,
ffind, pyped, django-admin.py...), the execute in a split second.

I can't even SEE the different between:

python3 -c "import os; [print(x) for x in os.listdir('.')]"

and

ls .

I'm having a hard time understanding how the Python VM startup time can
be perceived as a barriere here. I can understand if you have an
application firing Python 1000 times a second, like a CGI service or
some kind of code exec service. But scripting ?

Now I can imagine that a given Python program can be slow to start up,
because it imports a lot of things. But not the VM itself.


> 
> -brett
> 
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