More excellent work by the Go team!

[Robert Engels]

I had the opportunity to revisit my interface dispatch benchmark (https://github.com/robaho/go-dispatch-test).

Previously, the dispatching using pointer receivers was nearly 3x slower (i.e. 5.5 ns to 12.6 ns):

goos: darwin

goarch: amd64

pkg: github.com/robaho/go-dispatch-test

BenchmarkIDispatch-8 300000000 5.56 ns/op

BenchmarkDispatch-8 2000000000 1.57 ns/op

BenchmarkArrayParms-8 200000 9265 ns/op

PASS

and

goos: darwin

goarch: amd64

pkg: github.com/robaho/go-dispatch-test

BenchmarkIDispatch-8 100000000 12.6 ns/op

BenchmarkDispatch-8 2000000000 1.57 ns/op

PASS

With the latest Go 1.22.4, the performance difference has reversed ! (tests have been combined for simplicity).

goos: darwin

goarch: amd64

pkg: github.com/robaho/go-dispatch-test

cpu: Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz

BenchmarkIDispatch-8 535263746 2.118 ns/op

BenchmarkIDispatchPtr-8 675721244 1.773 ns/op

BenchmarkDispatch-8 1000000000 0.6953 ns/op

BenchmarkArrayParms-8 184212 6440 ns/op

PASS

Pretty impressive work. The interface based dispatch is almost equal to the Java version now:

Benchmark Mode Cnt Score Error Units

TestJavaDispatch.TestArrayDispatch avgt 3 4775.994 ± 13310.309 ns/op

TestJavaDispatch.TestDispatch avgt 3 0.941 ± 0.088 ns/op

TestJavaDispatch.TestIDispatch avgt 3 1.331 ± 0.146 ns/op

[Brian Candler]

> 4775.994 ± 13310.309

Those are pretty wide error bars though...

[Robert Engels]

Yep. Haven’t dig into it. I assume it has to do with allocations. That it is 2x faster than Go is somewhat suspect as well. 

I was more sharing for the change in Go performance. 

On Jun 21, 2024, at 2:11 PM, 'Brian Candler' via golang-nuts <golan...@googlegroups.com> wrote:

> 4775.994 ± 13310.309

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[robert engels]

Thanks for point it out Brian. I must of had some background interference. I re-ran the tests, Go was the same, Java is

Benchmark                           Mode  Cnt     Score    Error  Units

TestJavaDispatch.TestArrayDispatch  avgt    9  4367.196 ± 50.227  ns/op

TestJavaDispatch.TestDispatch       avgt    9     0.942 ±  0.005  ns/op

TestJavaDispatch.TestIDispatch      avgt    9     1.341 ±  0.040  ns/op

So the error is much less.

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