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From "Andrew Zhang" <zhanghuang...@gmail.com>
Subject Re: [optimization] Algorithmic tricks
Date Wed, 26 Jul 2006 11:50:33 GMT
On 7/25/06, Anton Luht <anton.luht@gmail.com> wrote:
> Hello,
> I'd like to suggest people that know some algorithmic tricks to look
> at the corresponding areas of classlib. Maybe some of the community
> members had (un)lucky experience of tuning performance of some
> application that led them to a deep knowledge of some very specific
> area has good approaches but not too widely known to an average
> developer. It might also be an interest for students and other people
> from institutes and universities.
> What I'm talking about is not related to 'premature optimization' that
> is now being discussed in another thread but something very narrow,
> limited to maybe one method and not influencing anything else.
> For example, consider current implementation of
> java.util.BitSet.cardinality() . It just checks all bits one by one
> and increments count. [1] Gives an overview of algorithms for checking
> set bit count. The fastest algorithms are with table lookup, which
> requires additional memory, but there are algorithms that are several
> times faster than iteration (in C) and don't require tables.


 I believe
> such local optimizations with good comments and links to corresponding
> resources won't do any harm and are a good point to start with.
> Does it make sence?

Yes. But I don't think it's time to shift too much efforts to this area now.
As you mentioned  above, we are glad to see if anyone volunteers to do such
kind of things.

I also suggest to focus on proper codes, which are hot or core. Never waste
time on seldom executed codes. :)


[1] http://www-db.stanford.edu/~manku/bitcount/bitcount.html
> --
> Regards,
> Anton Luht,
> Intel Middleware Products Division
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Andrew Zhang
China Software Development Lab, IBM

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