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Subject: Re: [Primitives] Does anyone use this?
From: Brian Pontarelli <brian@pontarelli.com>
In-Reply-To: <BLU142-W129AB1C2E96A96F83B5E8AE490@phx.gbl>
Date: Tue, 2 Nov 2010 11:54:17 -0600
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To: "Commons Users List" <user@commons.apache.org>

The autoboxing process mostly. When ints are autoboxed and unboxed, =
there is a performance hit because it does method invocations and =
instantiation. Autoboxing for some values will hit a cache to reduce =
instantiation overhead, but I think that is only for numbers < 256.=20

I've found that Lists, Maps and Sets that work directly on primitives =
reduce overhead quite a bit by removing the instantiation for the =
autoboxing and the method invocation for unboxing.

Of course, it all depends on the size and volume of access. I have a =
Trie that used a Map<Character, Trie> internally and I switched it to a =
primitive char map and it increased performance by about 20-30% and =
reduced memory consumption as well.

-bp


On Nov 2, 2010, at 11:41 AM, Martin Gainty wrote:

>=20
> Brian
>=20
> how does primitive collections implementation perform better than JDK =
collections?
>=20
> thanks,
> Martin=20
> ______________________________________________=20
> please do not alter or disrupt this transmission. thank you
>=20
>=20
>=20
>=20
>=20
>> Subject: Re: [Primitives] Does anyone use this?
>> From: brian@pontarelli.com
>> Date: Tue, 2 Nov 2010 11:32:01 -0600
>> To: user@commons.apache.org
>>=20
>> I would assume once you get out of the autoboxing caches the =
performance will get even worse. It really depends on the application, =
but I've found a number of spots where primitive collections work much =
better than autoboxing and JDK collections.
>>=20
>> -bp
>>=20
>>=20
>> On Nov 2, 2010, at 11:25 AM, James Carman wrote:
>>=20
>>> Yet another dependency to add to the mix.
>>>=20
>>> On Tue, Nov 2, 2010 at 1:17 PM, Cogen, David - 1008 - MITLL
>>> <cogen@ll.mit.edu> wrote:
>>>>=20
>>>> ________________________________________
>>>> From: jcarman@carmanconsulting.com [jcarman@carmanconsulting.com] =
On Behalf Of James Carman [james@carmanconsulting.com]
>>>> Sent: Tuesday, November 02, 2010 12:30 PM
>>>> To: Commons Users List
>>>> Subject: Re: [Primitives] Does anyone use this?
>>>>=20
>>>> Premature optimization with JDK5. I'd say stick to the JDK classes =
if
>>>> you can and only try to beef up space/performance if you need to.
>>>>=20
>>>>=20
>>>> Normally I agree about evils of premature optimization. But =
ArrayListInt is practically a drop-in replacement for ArrayList<Integer> =
and I see no reason not to use it if it is supported and reliable.
>>>>=20
>>>> My test of 2 billion accesses (reads and writes) ran in 35% of the =
time when I used ArrayListInt vs. ArrayList<Integer>.
>>>> =
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>>>>=20
>>>>=20
>>>=20
>>> =
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>>>=20
>>=20
>>=20
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>>=20
> 		 	   		 =20


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