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 <[email protected]> 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 <[email protected]>
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 [email protected].
>> 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 [email protected].
To view this discussion visit
https://groups.google.com/d/msgid/golang-nuts/CAJkBz4U7UiF5soicANW5GXmtLbyaw7Gi_6bu0kK5%2BpU1Kh_45A%40mail.gmail.com.
