For future reference: https://github.com/golang/go/issues/73137
Le samedi 2 août 2025 à 01:30:07 UTC+2, Pierre Durand a écrit : > OK, thank you everyone :) > > Le samedi 2 août 2025 à 01:02:41 UTC+2, peterGo a écrit : > >> On Friday, August 1, 2025 at 4:39:17 PM UTC-4 Pierre Durand wrote: >> >> I think it's related to the fact that b.Loop() disables some >> optimizations, but I'm not sure. >> >> >> Pierre, >> >> The difference between b.N and b.Loop is a known issue. It is by design, >> >> https://groups.google.com/g/golang-nuts/c/Z017c0f59vY/m/AY1-wT0OBAAJ >> >> Peter >> >> >> Le vendredi 1 août 2025 à 22:33:56 UTC+2, Pierre Durand a écrit : >> >> I can reproduce the issue with this code >> https://github.com/pierrre/go-libs/blob/31bec3f12a86382924cc0b486c2008db062a14bd/runtimeutil/runtimeutil_test.go#L101-L118 >> Sorry I can't write a smaller code snippet, because I think it's related >> to escape analysis, and I don't fully understand it. >> >> As you can see, I'm benchmarking the same function WriteFrames() with the >> old and the new benchmarking methods. >> >> When I run the benchmark, here is the result >> >> go test -v -run=^$ -bench="^BenchmarkWriteFrames" -benchmem ./runtimeutil >> goos: linux >> goarch: amd64 >> pkg: github.com/pierrre/go-libs/runtimeutil >> cpu: Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz >> BenchmarkWriteFrames >> BenchmarkWriteFrames-12 366825 3091 ns/op >> 0 B/op 0 allocs/op >> BenchmarkWriteFramesNew >> BenchmarkWriteFramesNew-12 328620 3445 ns/op >> 80 B/op 4 allocs/op >> PASS >> ok github.com/pierrre/go-libs/runtimeutil 2.303s >> >> >> >> Le ven. 1 août 2025 à 22:04, Junyang Shao <shaoj...@google.com> a écrit : >> > >> > Hello Pierre, >> > >> > Thank you for bringing up this issue. >> > >> > May you share the code snippet that triggers this behavior? Thanks. >> >> > >> > On Fri, Aug 1, 2025 at 12:50 PM Pierre Durand <pierre...@gmail.com> >> wrote: >> >> >> >> Hello >> >> >> >> I noticed a weird behavior when I'm benchmarking with testing.B.Loop() >> code that uses iterators . >> >> The benchmark shows allocations where I start to iterate the iterator, >> and where I declare variables (before the loop) that are used inside the >> iterator loop. >> >> I know that my code is not doing any allocation, so it's strange. >> >> If I change my benchmark to use the old "range b.N", then it doesn't >> show this strange behavior. >> >> If I check allocations with "testing.AllocsPerRun", I don't see any >> allocation. >> >> >> >> Is that a know issue ? Should I open a bug ? >> >> What should I do ? Use the old benchmarking method ? >> >> >> >> Regards >> >> >> >> -- >> >> You received this message because you are subscribed to the Google >> Groups "golang-nuts" group. >> >> To unsubscribe from this group and stop receiving emails from it, send >> an email to golang-nuts...@googlegroups.com. >> >> To view this discussion visit >> https://groups.google.com/d/msgid/golang-nuts/70456dc1-3380-40fd-951d-e52275bc48a5n%40googlegroups.com >> . >> > >> > >> > >> > -- >> > Thanks, >> > Junyang >> >> >> >> -- >> Pierre Durand >> >> -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/golang-nuts/42ce6358-792b-488c-a763-cd0eb1bc26fcn%40googlegroups.com.
