Document "showPprofLabels" debug configuration attribute

[gm0stache]

Update the launch configuration attributes (in package.json) and debug documentation to reflect the fact that showPprofLabels is a valid configuration value for debugging.

Original description

Is your feature request related to a problem? Please describe.
Pprof labels are not (directly) visible in the call stack section of the debugger.

Describe the solution you'd like
I would like the Pprof labels to be visible in the call stack section of the debugger.

Consider the following program:

package main

import (
	"context"
	"fmt"
	"runtime/pprof"
	"strconv"
	"sync"
	"time"
)

func worker(name string) {
	time.Sleep(1 * time.Second)
	fmt.Println("worker finished:", name)
}

func main() {
	wg := sync.WaitGroup{}
	for i := 0; i < 20; i++ {
		wg.Add(1)
		labels := pprof.Labels("worker", strconv.Itoa(i))
		pprof.Do(context.TODO(), labels, func(ctx context.Context) {
			go worker(strconv.Itoa(i))
		})
	}
	wg.Wait()
}

lauch profile:

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Launch file",
            "type": "go",
            "request": "launch",
            "mode": "debug",
            "program": "${file}",
            "hideSystemGoroutines": true,
            "showPprofLabels": [
                "*"
            ]
        }
    ]
}

When setting a breakpoint for last line im the main function, and debugging the program, I would like to see the goroutines listed in the call stack section with the configured pprof labels clearly visible. It would make debugging goroutines more straight forward.

Additional context

• the lauch profile prop showPprofLabels is not officially supported (maybe do so?), but I used it based on information from this issue: How to enable new pprof labels features? #3173

Thanks for all your work and time!
Happy to answer any upcoming questions!

BR
Gabriel

[AlexanderYastrebov]

Why not enable labels by default?

[firelizzard18]

Can you show a screenshot explaining what you're looking for? I didn't know showPprofLabels was a thing and I'm unclear what works and what doesn't work. What does showPprofLabels do? Where are the labels shown? And where are they currently not shown?

Regardless, I'm pretty sure this is a change that needs to be made in delve, since it controls almost every aspect of debugging and of what is shown during a debugging session.

[AlexanderYastrebov]

I wanted to see pprof goroutine labels (ref zalando/skipper#3626) so I've created launch configuration

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": "run-selected-test",
            "type": "go",
            "request": "launch",
            "mode": "test",
            "program": "${fileDirname}",
            "args": [
                "-test.run",
                "^${selectedText}"
            ],
            "hideSystemGoroutines": true,
            "showPprofLabels": [
                "*"
            ]
        }

    ]
}

and then run my test (by selecting it) and see goroutine labels in the callstack (note trace_id:2b):

Regardless, I'm pretty sure this is a change that needs to be made in delve, since it controls almost every aspect of debugging and of what is shown during a debugging session.

Right, from the discussion I found its a dlv config value

https://github.com/go-delve/delve/blob/f32818c9e36e6c6e84a07131c08f994ee38fa156/service/dap/command.go#L67-L72

One improvement could be to remove Property showPprofLabels is not allowed error message:

[firelizzard18]

Making showPprofLabels appear as a real config value is easy, it's as simple as adding a property to the launch configurationAttributes (and maybe also to the attach configuration attributes).

Is that all that's needed? The feature request says make labels "visible in the call stack section of the debugger"; but they are visible in the call stack session as per your screenshot, which is why I'm unsure what is missing. Is the goal simply to make showPprofLabels 'official' and possibly set a default value? Or is there something else that's missing?

[gm0stache]

@firelizzard18
I guess I was too stupid to figure out the property in the configuration - totally enough for my use-cases!
thanks so much for all your work!
BR Gabriel

[firelizzard18]

@gm0stache It's certainly not stupidity to not know about an undocumented configuration value, I was just confused because it sounded like you had what you needed. This definitely should be documented better and might be valuable to show labels by default, so I'll update the issue to reflect that.