Thanks for pointing me in that direction, this definitely contributes. I
locally replaced golang.org/x/net with a version that does not use
html/template and now the RSS of my program is down to 7588 KB. So there's
still quite a bit of delta to what it was before importing grpc. As I can't
really see anything with pprof I assume this is mostly down to init()? I
just found out about GODEBUG=inittrace=1 so I counted those allocations up
and got to ~2625 KB:
$ GODEBUG=inittrace=1 go run . &| awk '{b+=$8} END {print b}'
2625600
Now there's still around 3275 KB unaccounted for.
Cyrill
On Sunday, August 24, 2025 at 2:43:10 AM UTC+2 Ian Lance Taylor wrote:
> On Sat, Aug 23, 2025 at 5:09 PM Cyrill Troxler <cyrill...@gmail.com>
> wrote:
> >
> > I noticed that simply importing certain modules can substantially
> increase observed RSS even though nothing is visibly being allocated on the
> heap when looking at pprof. For example, take the following program:
> >
> > ```
> > package main
> >
> > import (
> > "time"
> > )
> >
> > func main() {
> > time.Sleep(time.Hour)
> > }
> > ```
> >
> > Running this with go 1.24.6 and running it shows an RSS of 1688 KB
> (using ps).
> >
> > ```
> > VSZ RSS
> > 1225172 1688
> > ```
> >
> > Now as an example, I just add the following import: `_ "
> google.golang.org/grpc"`
> >
> > The RSS of the otherwise same program looks like this:
> >
> > ```
> > VSZ RSS
> > 1646164 9896
> > ```
> >
> > First off, what exactly is causing this rather big increase in RSS here?
> Is there any way to reduce this and if not, what is the best way to find
> such heavy dependencies?
> >
> > I have used https://github.com/Zxilly/go-size-analyzer with some
> success but this just looks at the binary size and is not very granular,
> e.g. I have no way of knowing what exactly inside of the grpc module is
> causing this.
>
> I didn't double check, but this could be a version of
> https://go.dev/issue/62024.
>
> Ian
>
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