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Re: Mac vs. Linux for Python Development

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Date Sun, 2 Mar 2014 20:58:52 +1100
Subject Re: Mac vs. Linux for Python Development
From Chris Angelico <rosuav@gmail.com>
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On Sun, Mar 2, 2014 at 6:35 PM, Frank Millman <frank@chagford.com> wrote:
> I assume by 'warm cache' you mean that I had used the decimal module before
> and not switched the machine off before trying the above exercise.
>
> In my case, the machine was switched off before I started. I switched it on
> and executed the above steps.

That would be about it, yeah. So that would be a cold cache test.

> To be slightly more precise, instead of 'the blink of an eye', I estimate it
> was between 250-500 ms. If I close the interpreter and start it up again, it
> takes maybe 100-200ms.

Alright, so now we're talking about some other factors on my system
that slow down the cold cache load dramatically. That I can completely
understand; when I originally posted it, I was fully aware that the
exact figures wouldn't be duplicable. 500ms is a major delay to
startup; but what's really significant is the 100-200ms warm cache,
because that one is what's going to be repeated. (Imagine a web server
that periodically restarts its subprocesses - say, every N requests.
Adding 200ms to startup time effectively adds 200/N ms to every
request.)

An awesome disk cache can improve that immensely, though. My Debian
box, warm cache, takes 0.0 seconds to import decimal. But it's a
faster computer overall, so even cold cache it only takes a hundred ms
or so.

> Just to be sure, I switched the machine off and on again, and repeated the
> exercise. Starting the interpreter for the first time takes 1.5 - 2 seconds.
> Importing decimal for the first time takes less than 500ms.

I'm beginning to get a suspicion here that the Windows XP disk cache
actually might have a "most pessimal" state, where it's full of other
stuff. Worse than a cold cache in performance, a cache warmed by
something else. But in any case, the exact figures for cold cache are
almost immaterial compared to a noticeable warm-cache delay - if
there's enough work to be done just loading the .pyc from the disk
cache that it takes visible time, then it would be a problem to force
that to be loaded on every interpreter startup. Which was kinda the
point of my original testing - I wanted to know how much of a penalty
there'd be to moving decimal to built-in.

ChrisA

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Thread

Mac vs. Linux for Python Development twiz <twizansk@gmail.com> - 2014-02-23 00:43 -0800
  Re: Mac vs. Linux for Python Development Chris Angelico <rosuav@gmail.com> - 2014-02-23 19:58 +1100
    Re: Mac vs. Linux for Python Development twiz <twizansk@gmail.com> - 2014-02-23 02:17 -0800
      Re: Mac vs. Linux for Python Development Chris Angelico <rosuav@gmail.com> - 2014-02-23 21:24 +1100
      Re: Mac vs. Linux for Python Development Ned Deily <nad@acm.org> - 2014-02-23 03:49 -0800
  Re: Mac vs. Linux for Python Development Andriy Kornatskyy <andriy.kornatskyy@live.com> - 2014-02-23 11:51 +0200
  Re: Mac vs. Linux for Python Development "Günther Dietrich" <gd.usenet@spamfence.net> - 2014-02-23 12:34 +0100
  Re: Mac vs. Linux for Python Development Dave Cook <davecook@nowhere.net> - 2014-02-24 03:37 +0000
  Re: Mac vs. Linux for Python Development William Ray Wing <wrw@mac.com> - 2014-02-24 10:33 -0500
  Re: Mac vs. Linux for Python Development Michael Torrie <torriem@gmail.com> - 2014-02-24 10:34 -0700
  Re: Mac vs. Linux for Python Development Michael Torrie <torriem@gmail.com> - 2014-02-24 10:42 -0700
  Re: Mac vs. Linux for Python Development Chris Angelico <rosuav@gmail.com> - 2014-02-25 05:37 +1100
    Re: Mac vs. Linux for Python Development Grant Edwards <invalid@invalid.invalid> - 2014-02-24 19:35 +0000
  Re: Mac vs. Linux for Python Development Roy Smith <roy@panix.com> - 2014-02-23 09:20 -0500
  Re: Mac vs. Linux for Python Development "Mark H. Harris" <harrismh777@gmail.com> - 2014-03-01 14:32 -0800
    Re: Mac vs. Linux for Python Development Chris Angelico <rosuav@gmail.com> - 2014-03-02 09:57 +1100
    Re: Mac vs. Linux for Python Development Ned Deily <nad@acm.org> - 2014-03-01 15:07 -0800
    Re: Mac vs. Linux for Python Development "Frank Millman" <frank@chagford.com> - 2014-03-02 07:51 +0200
    Re: Mac vs. Linux for Python Development Chris Angelico <rosuav@gmail.com> - 2014-03-02 17:57 +1100
    Re: Mac vs. Linux for Python Development "Frank Millman" <frank@chagford.com> - 2014-03-02 09:35 +0200
    Re: Mac vs. Linux for Python Development Chris Angelico <rosuav@gmail.com> - 2014-03-02 20:58 +1100

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