runtime: cpu sample has wrong descripting comment in the code #58327
Description
What version of Go are you using (go version)?
$ go version go version go1.19.5 linux/amd64
Does this issue reproduce with the latest release?
Yes, I got the same result with go 1.20.
What did you do?
I have program:
package main
import (
"os"
"runtime"
"runtime/trace"
)
func main() {
runtime.SetCPUProfileRate(100)
err := trace.Start(os.Stdout)
if err != nil {
panic(err)
}
for i := 0; i < 10000; i++ {
for j := 0; j < 10000; j++ {
_ = i + j
}
}
defer trace.Stop()
}The program provides a trace file as output.
What did you expect to see?
I expect Cpu samples in the trace file will be in the format (as in the source code of trace tool):
EvCPUSample = 49 // CPU profiling sample [timestamp, stack, real timestamp, real P id (-1 when absent), goroutine id]I.e. stack is second, real timestamp is third.
What did you see instead?
Instead, I see the following events in the trace file:
event type: 49, args: [11 1755437435756 0 1 15]
event type: 49, args: [10 1755437928681 0 1 15]
event type: 49, args: [4 1755438251486 0 1 15]
So seems like real timestamp is on the second position, but more essential there is no stack id!