[jira] [Commented] (RNG-72) Create a RandomSource.create benchmark

["Alex D Herbert (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/RNG-72?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16781569#comment-16781569 ] 

Alex D Herbert commented on RNG-72:
-----------------------------------

Note: The original benchmark of construction and generation used the assumption that adding times from two benchmarks was valid.

I ran a check using construction and generation in the same benchmark and found an error in the original analysis where construction cost was inflated relative to generation cost by 500. This led to invalid conclusions about the number of values that have to be created before the cost of building the generator is lost.

That post has been deleted and a new post will be added with correct analysis.


> Create a RandomSource.create benchmark
> --------------------------------------
>
>                 Key: RNG-72
>                 URL: https://issues.apache.org/jira/browse/RNG-72
>             Project: Commons RNG
>          Issue Type: New Feature
>          Components: simple
>    Affects Versions: 1.3
>            Reporter: Alex D Herbert
>            Assignee: Alex D Herbert
>            Priority: Minor
>              Labels: performance-benchmark
>             Fix For: 1.3
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> The recommended method to construct a {{UniformRandomProvider}} is to use, e.g.:
> {code:java}
> import org.apache.commons.rng.UniformRandomProvider;
> import org.apache.commons.rng.simple.RandomSource;
> UniformRandomProvider rng = RandomSource.create(RandomSource.MWC_256);
> {code}
> The factory method knows the type of seed required for the constructor and generates one as appropriate.
> This factory method could be made more efficient, in particular:
>  * Reducing synchronisation around the single source of random seed data
>  * Adding knowledge of the required seed size for arrays
>  * Changing internal data structures, e.g. {{Map<Class<?>, SeedConverter<?,?>>}} can be changed to {{Map<SeedType, SeedConverter<?,?>>}} using an {{EnumMap}} if a new enum {{SeedType}} was created for all the supported seeds (currently 4 types).
>  * Add a new interface to replace {{SeedConverter<?,?>.convert()}} with a {{.convert(int outputArraySize)}} method to allow conversions to generate appropriately sized arrays. The parameter can be ignored for non-array conversions but could optimise array conversions.
> This ticket is to add a JMH benchmark to compare the speed of construction of all the providers using:
>  * Their native constructor
>  * {{RandomSource}} using the native seed of the correct size (calls a constructor using reflection)
>  * {{RandomSource}} using a non native seed (requires seed conversion)
>  * {{RandomSource}} using no seed (requires seed generation)
> The report will be posted here. It could be added to the user guide for reference.
> This work is motivated by the new {{XorShiRo}} generators in version 1.3 that have a native array seed size of 2, 4, or 8. The current {{RandomSource}} create method will generate a fixed seed of length 128 for seeding.



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