Re: Parallel arrays revisited

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 12 Oct 2010 23:27:29 -0400

Message-ID:

<i938qr$mvb$1@news.albasani.net>

Eric Sosman wrote:

Now, if the loop runs its thousand iterations each time its
method is called, and if the method is called a thousand times each
time its bean is used, and if the bean is used a thousand times
a day on each of a thousand machines ... Sadly, though, I see
programmers (myself included!) diligently optimizing their static
initializers ...

There's good optimization (algorithmic) and bad optimization (micro-managed).
It's never too early for the first kind.

Immutability is part of a toolkit of idioms to construct stable, extensible
systems that are inevitability about as fast as you can safely get. It's
especially handy for the large class of real-world applications that are
multi-threaded.

Good optimization of static initializers is structural rather than
cycles-based. You use static final initializers of immutable instances to
spread immutability. A special class of those are compile-time constants,
which have consequences for /happens-before/ relationships. Initialization
order matters, especially in enums. These optimize for correctness, but
properly done they do tend to make the program fast.

Remember, too, that there are different kinds of fast.

--
Lew