ClassValue perf?

[Michael Haupt]

Hi Jochen,

> Am 29.04.2016 um 14:42 schrieb Jochen Theodorou <blackdrag at gmx.org>:
> On 29.04.2016 13:19, Michael Haupt wrote:
>> Hi Jochen,
>> 
>>> Am 29.04.2016 um 12:17 schrieb Jochen Theodorou <blackdrag at gmx.org
>>> <mailto:blackdrag at gmx.org>>:
>>> my fear is a bit that having only a single value, will not be enough
>>> if you have for example multiple dynamic languages running... let's
>>> say Nashorn, JRuby, and Groovy. Also, if I ever get there, using
>>> multiple values would become a normal case in Groovy.
>>> 
>>> So any size depending optimization looks problematic for me
>> 
>> I may misunderstand you here - note the patch does not introduce a
>> single-value *only* ClassValue. The patch is meant to introduce a
>> special case for as long as there is only one value associated with a
>> class. As soon as a second value comes in, the ClassValue will
>> transition to the usual map storage.
>> 
>> Please let me know if this is a response to your concern.
> 
> how does performance compare to cases of 2-12 values?

OK, I'm still not sure if there was a misunderstanding or not, and whether my response has clarified that. Please let me know.

To answer your question, see the numbers reported in http://cr.openjdk.java.net/~mhaupt/8031043/bench-results.txt - I'm not going to quote them in full detail here, but overall the numbers for 2, 4, and 16 values are on par for the randomGenerator and sequentialGenerator benchmarks, and show slightly better performance (on the order of 1ns) for the twisti and plevart patches.

Best,

Michael

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