JRuby to Java invokedynamic dispatch

[Attila Szegedi]

Woo-hoo!

On Jun 8, 2011, at 9:48 PM, Charles Oliver Nutter wrote:

> Hello friends! I have another update!
> 
> I've just landed preliminary work to make JRuby directly bind Ruby to
> Java calls that were normally done via reflection! Currently only
> no-arg methods that return primitives, CharSequence/String, or void
> get patched straight through, but in those cases it makes a solid
> performance difference.
> 
> Here's two benchmarks before direct binding and after:
> 
> BEFORE (using invokedynamic, but bound to a DynamicMethod wrapper
> around java.lang.reflect.Method
> 
> Measure System.currentTimeMillis, long becoming Fixnum
>  0.277000   0.000000   0.277000 (  0.278000)
>  0.188000   0.000000   0.188000 (  0.188000)
>  0.191000   0.000000   0.191000 (  0.191000)
>  0.221000   0.000000   0.221000 (  0.221000)
>  0.198000   0.000000   0.198000 (  0.199000)
> Measure java.lang.Thread#name, String entering Ruby
>  0.520000   0.000000   0.520000 (  0.520000)
>  0.380000   0.000000   0.380000 (  0.380000)
>  0.383000   0.000000   0.383000 (  0.383000)
>  0.378000   0.000000   0.378000 (  0.378000)
>  0.388000   0.000000   0.388000 (  0.389000)
> 
> AFTER (using invokedynamic and MHs all the way to the target)
> 
> Measure System.currentTimeMillis, int becoming Fixnum
>  0.173000   0.000000   0.173000 (  0.172000)
>  0.126000   0.000000   0.126000 (  0.126000)
>  0.137000   0.000000   0.137000 (  0.137000)
>  0.148000   0.000000   0.148000 (  0.148000)
>  0.147000   0.000000   0.147000 (  0.147000)
> Measure java.lang.Thread#name, String entering Ruby
>  0.521000   0.000000   0.521000 (  0.521000)
>  0.276000   0.000000   0.276000 (  0.276000)
>  0.274000   0.000000   0.274000 (  0.274000)
>  0.274000   0.000000   0.274000 (  0.274000)
>  0.276000   0.000000   0.276000 (  0.276000)
> 
> In the latter case, this is only a tiny bit slower than a JRuby core
> class method that constructs a Ruby String, so the dispatch overhead
> of Ruby to Java has almost completely disappeared! Amazing!
> 
> This can be disabled with jruby.invokedynamic.java=false, but since
> it's showing such a good perf improvement I've got it on by default
> right now.
> 
> - Charlie
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