How to profile benchmarks using the pprof tool?

Question

I want to profile my benchmarks generated by go test -c, but the go tool pprof needs a profile file usually generated inside the main function like this:

func main() {
    flag.Parse()
    if *cpuprofile != "" {
        f, err := os.Create(*cpuprofile)
        if err != nil {
            log.Fatal(err)
        }
        pprof.StartCPUProfile(f)
        defer pprof.StopCPUProfile()
    }

How can I create a profile file within my benchmarks ?

Answer 1

As described in https://pkg.go.dev/cmd/go#hdr-Testing_flags you can specify the profile file using the flag -cpuprofile.

For example

go test -cpuprofile cpu.out