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From: Jan Burse <janburse@fastmail.fm>
Newsgroups: comp.lang.java.programmer
Subject: Re: setSize ArrayList, when will it come?
Date: Thu, 11 Aug 2011 01:52:28 +0200
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Joshua Cranmer schrieb:
> On 8/10/2011 1:37 PM, Jan Burse wrote:
>> Look see: Migrating from Vector to ArrayList is all
>> about energy saving. ArrayList does not use synchronized,
>> therefore it does use less CPU. But in my case the
>> migration is not perfect, since setSize() is missing.
>
> We have given *several* ways to re-emulate setSize using ArrayList.
> Since moving from Vector to ArrayList causes savings in loss of
> synchronized, perhaps the speed slowdown in your emulations is more than
> made up for.
>

If the emulation eats up the speed gain of the remove the
synchronization, then there is no use in doing the migration
at all. The synchronization primitive in Java is already
highly optimized, it has a fastpath in the non-competitive
case. Removing synchronization gives some performance gain,
but it is in the range of 5-20% only nowadays. It depends of
course on how much synchronization the original application used.

So the chances are very high, that an emulation eats up
exactly these 5-20% percents.

Bye