Plot not starting at t=0 when there are error responses

[mightyguava]

Version and Runtime

v12.3.0@7bf09f4fab4d852141935796455c17459d212098

Expected Behaviour

vegeta plot creates a graph at t=0

Actual Behaviour

vegeta plot created a graph starting at t=892

exp-009-read.html.zip

Steps to Reproduce

I used vegeta as a library in my load test, against DynamoDB, to test what happens when requests go over the provisioned capacity. My requests started getting throttled at around the 15 minute mark, which is exactly where the plot starts. I'm guessing a bug in plotting specifically.

Unfortunately I can't share the repo, but the setup I think is pretty standard:

func main() {
	rate := vegeta.Rate{Freq: flags.RPS, Per: time.Second}
	duration := flags.Duration
	sess := session.Must(session.NewSession(&aws.Config{
		Region: &flags.AWSRegion,
	}))
	svc := dynamodb.New(sess)
	attacker := vegeta.NewAttacker()

	var res <-chan *vegeta.Result
	switch flags.Op {
	case "write":
		targeter := loadtest.DynamoWriteTargeter(svc, flags.TableName)
		res = attacker.Attack(targeter, rate, duration, "PutItem")
	case "read":
		targeter, err := loadtest.DynamoReadTargeter(svc, flags.TableName, flags.ReadSetSize)
		if err != nil {
			return errors.Wrapf(err, "failed to create read targeter")
		}
		res = attacker.Attack(targeter, rate, duration, "GetItem")
	default:
		logrus.Fatalf("invalid op %s", flags.Op)
	}
	sig := make(chan os.Signal, 1)
	signal.Notify(sig, os.Interrupt)

	var out io.WriteCloser
	out, err := file(flags.Out, true)
	if err != nil {
		return err
	}
	defer out.Close()
	if strings.HasSuffix(flags.Out, ".gz") {
		out = gzip.NewWriter(out)
		defer out.Close()
	}
	enc := vegeta.NewEncoder(out)

encodeLoop:
	for {
		select {
		case <-sig:
			attacker.Stop()
			return nil
		case r, ok := <-res:
			if !ok {
				break encodeLoop
			}
			if err := enc.Encode(r); err != nil {
				return err
			}
		}
	}
}

[tsenart]

Would you be able to store your results in a file with the response body and other sensitive data elided? Sharing that with me would really help debugging.

[mightyguava]

Sure, here's the results gzipped in gob format. https://s3-us-west-2.amazonaws.com/yunchi-dynamodb-test/exp-009-stripped.bin.gz