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From "Mikhail Loenko" <mloe...@gmail.com>
Subject Re: Re: Re: [classlib] TwoKeyHashMap
Date Tue, 25 Jul 2006 07:32:46 GMT
2006/7/25, Alex Blewitt <alex.blewitt@gmail.com>:
> On 25/07/06, Mikhail Loenko <mloenko@gmail.com> wrote:
> > In general before we get rid of that class or decide to keep it, I think
> > we should work out an approach to performance optimizations.
> >
> > It's a rare case when perofmance might be significantly improved for free,
> > a regular price is: additional complexity, more code, lack of readability,
> > additional memory footprint etc.
> >
> > So let's discuss how we approach performance in general and that return to
> > this specific class.
>
> Performance in general: premature optimisation is the root of all evil [Knuth]
> http://mindprod.com/jgloss/knuth.html
>
> In this case, we've not only dupllicated logic from a HashMap, but at
> the expense of a potential problem that we've not even measured. For
> example, there is an assumption that the cost of creating (and
> recycling) objects in a wrapper for an equivalent use of a Map is
> something that's not even been measured, yet we have code that assumes
> that that is a bottleneck.
>
> Is this code even on the critical path? That is, have we profiled this
> code to know whether any access is actually directly responsible for
> performance problems? If not, then it sounds like assumptions have
> been made prior to writing this.
>
> So, we should strive to make code:
>
> 1) Correct
> 2) Easy to understand and maintain
> 3) Performant
> 4) Optimised (for memory, speed)
>
> in that order. In this case, I'm not sure whether we've violated 2 in
> preference for 4.

Not sure I agree with your priorities

Thanks,
Mikhail

>
> Alex.
>
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