[Python-Dev] Python startup time

[Brett Cannon]

On Sat, Jul 22, 2017, 07:22 Steve Dower, <steve.dower at python.org> wrote:

> I believe the trend is due to language like Python and Node.js, most of
> which aggressively discourage threading (more from the broader community
> than the core languages, but I see a lot of apps using these now), and also
> the higher reliability afforded by out-of-process tasks (that is, one crash
> doesn’t kill the entire app – e.g browser tabs).
>
>
>
> Optimizing startup time is incredibly valuable, and having tried it a few
> times I believe that the import system (in essence, stat calls) is the
> biggest culprit. The tens of ms prior to the first user import can’t really
> go anywhere.
>

Stat calls in the import system were optimized in importlib a while back to
be cached in finders so at this point you will have to remove a stat call
to lower that cost or cache more which goes into breaking abstractions or
designing new APIs.

-brett


>
> Cheers,
>
> Steve
>
>
>
> Top-posted from my Windows phone
>
>
>
> *From: *Alex Walters <tritium-list at sdamon.com>
> *Sent: *Saturday, July 22, 2017 1:39
> *Cc: *'Python-Dev' <python-dev at python.org>
>
>
> *Subject: *Re: [Python-Dev] Python startup time
>
>
>
> > -----Original Message-----
>
> > From: Python-Dev [mailto:python-dev-bounces+tritium-
>
> > list=sdamon.com at python.org] On Behalf Of Paul Moore
>
> > Sent: Saturday, July 22, 2017 4:14 AM
>
> > To: David Mertz <mertz at gnosis.cx>
>
> > Cc: Barry Warsaw <barry at python.org>; Python-Dev <python-
>
> > dev at python.org>
>
> > Subject: Re: [Python-Dev] Python startup time
>
>
>
>
>
> > It's a bit of a chicken and egg problem - Windows users avoid
>
> > excessive command line program invocation because startup time is
>
> > high, so no-one optimises startup time because Windows users don't use
>
> > short-lived command line programs. But I'm seeing a trend away from
>
> > that - more and more Windows tools these days seem to be comfortable
>
> > spawning subprocesses. I don't know what prompted that trend.
>
>
>
> The programs I see that are comfortable spawning processes willy-nilly on
>
> windows are mostly .net, which has a lot of the runtime assemblies cached
> by
>
> the OS in the GAC - if you are spawning a second processes of yourself, or
>
> something that uses the same libraries as you, the compile step on those
> can
>
> be skipped.  Unless you are talking about python/non-.NET programs, in
> which
>
> case, I have no answer.
>
> > Paul
>
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