Open Stack

>All performance matters. All memory consumption matters. Being wasteful
over a purely aesthetic few extra characters of code is silly.

Isn't the logical conclusion of this to write everything in a different
language? :)

On Tue, Sep 13, 2016 at 8:42 AM, Terry Wilson <twilson at redhat.com> wrote:

> On Wed, Jun 10, 2015 at 4:41 AM, Robert Collins
> <robertc at robertcollins.net> wrote:
> > On 10 June 2015 at 21:30, Ihar Hrachyshka <ihrachys at redhat.com> wrote:
> >> -----BEGIN PGP SIGNED MESSAGE-----
> >> Hash: SHA256
> >>
> >> On 06/10/2015 02:15 AM, Robert Collins wrote:
> >>> I'm very glad folk are working on Python3 ports.
> >>>
> >>> I'd like to call attention to one little wart in that process: I
> >>> get the feeling that folk are applying a massive regex to find
> >>> things like d.iteritems() and convert that to six.iteritems(d).
> >>>
> >>> I'd very much prefer that such a regex approach move things to
> >>> d.items(), which is much easier to read.
> >>>
> >>> Here's why. Firstly, very very very few of our dict iterations are
> >>> going to be performance sensitive in the way that iteritems()
> >>> matters. Secondly, no really - unless you're doing HUGE dicts, it
> >>> doesn't matter. Thirdly. Really, it doesn't.
> >>>
> >>
> >> Does it hurt though? ;)
> >
> > Yes.
> >
> > Its: harder to read. Its going to have to be removed eventually anyway
> > (when we stop supporting 2.7). Its marginally slower on 3.x (it has a
> > function and an iterator wrapping the actual thing). Its unidiomatic,
> > and we get lots of programmers that are new to Python; we should be
> > giving them as beautiful code as we can to help them learn.
>
> If someone is so new they can't handle six.iteritems, they should stay
> away from Neutron code. It'll eat them.
>
> >>> At 1 million items the overhead is 54ms[1]. If we're doing inner
> >>> loops on million item dictionaries anywhere in OpenStack today, we
> >>> have a problem. We might want to in e.g. the scheduler... if it
> >>> held in-memory state on a million hypervisors at once, because I
> >>> don't really to to imagine it pulling a million rows from a DB on
> >>> every action. But then, we'd be looking at a whole 54ms. I think we
> >>> could survive, if we did that (which we don't).
> >>>
> >>> So - please, no six.iteritems().
>
> Huge -1 from me. The "I like looking at d.items() more than I like
> looking at six.iteritems(d) so make everything (even slightly) less
> efficient" argument is insane to me. All performance matters. All
> memory consumption matters. Being wasteful over a purely aesthetic few
> extra characters of code is silly.
>
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