github.com/rafaelhl/profiling-samples

Go Profiling Samples

Some samples implementations to illustrate how to use Go Profiling to improve a Go code.

Samples

This project has three implementations with issues performance common in a Go code.

JSON Unmarshalling sample

Simple implementation that will do a unmarshall multiple times as defined on param.

GET /json/unmarshall?times={times}

func Unmarshall[T any](times int) (result T) {
	file, err := os.ReadFile(fmt.Sprintf("%stest.json", Path))
	if err != nil {
		panic(err)
	}

	for i := 0; i <= times; i++ {
		err = json.NewDecoder(bytes.NewReader(file)).Decode(&result)
		if err != nil {
			panic(err)
		}
	}

	return
}

samples/json.go

Load location with timezone sample

Simple implementation that will load a location with tz multiple times as defined on param.

GET /timezone?times={times}

func Timezone(times int) (tz *time.Location) {
	for i := 0; i <= times; i++ {
		var err error
		tz, err = time.LoadLocation("America/Sao_Paulo")
		if err != nil {
			panic(err)
		}
	}

	return
}

samples/timezone.go

Allocations inside a loop sample

Simple implementation that will create an object and append on slice and iterate it multiple times as defined on param.

GET /aloc?times={times}

func Aloc[O any, T []O](obj O, times int) (result T) {

	for i := 0; i <= times; i++ {
		result = append(result, obj)
	}

	for _, o := range result {
		fmt.Printf("%+v\n", o)
	}

	return
}

samples/aloc.go

Using pprof

On this project we will use the HTTP pkg to run the pprof.

Starting the app

First we will start the app.

go run .

Running the pprof

To generate the pprof data and render it on a web page we have to execute passing the expected endpoint available with follow args:

go tool pprof -http=localhost: http://localhost:7777/debug/pprof/profile?seconds=60

Simulating HTTP requests

Now for the pprof data has some metrics we have to simulate some parallel requests immediately after run the pprof.

curl "http://localhost:7777/json/unmarshall?times=10000000" &
curl "http://localhost:7777/timezone?times=100000" &
curl "http://localhost:7777/aloc?times=1000000" &

Expected web page

After 60 seconds we have to be redirected to a web page as below:

https://youtu.be/hmD9zBjuc74 "Go tool pprof web interactive"

Pull requests with improvements of the samples

• Improve JSON route decode #1
• Improve timezone load #2
• Improve aloc processing route #3
• Validate an error avoiding returning any result with err #5