grafana/k6 · error

the duration must be at least %s, but is %s

Error message

the duration must be at least %s, but is %s

What it means

ConstantArrivalRateConfig.Validate found the duration shorter than minDuration (100ms). Arrival-rate executors enforce a minimum duration so the scheduling loop can meaningfully start iterations; very short durations are rejected outright.

Source

Thrown at lib/executor/constant_arrival_rate.go:106

}

// Validate makes sure all options are configured and valid
func (carc *ConstantArrivalRateConfig) Validate() []error {
	errors := carc.BaseConfig.Validate()
	if !carc.Rate.Valid {
		errors = append(errors, fmt.Errorf("the iteration rate isn't specified"))
	} else if carc.Rate.Int64 <= 0 {
		errors = append(errors, fmt.Errorf("the iteration rate must be more than 0"))
	}

	if carc.TimeUnit.TimeDuration() <= 0 {
		errors = append(errors, fmt.Errorf("the timeUnit must be more than 0"))
	}

	if !carc.Duration.Valid {
		errors = append(errors, fmt.Errorf("the duration is unspecified"))
	} else if carc.Duration.TimeDuration() < minDuration {
		errors = append(errors, fmt.Errorf(
			"the duration must be at least %s, but is %s", minDuration, carc.Duration,
		))
	}

	if !carc.PreAllocatedVUs.Valid {
		errors = append(errors, fmt.Errorf("the number of preAllocatedVUs isn't specified"))
	} else if carc.PreAllocatedVUs.Int64 < 0 {
		errors = append(errors, fmt.Errorf("the number of preAllocatedVUs can't be negative"))
	}

	if !carc.MaxVUs.Valid {
		// TODO: don't change the config while validating
		carc.MaxVUs.Int64 = carc.PreAllocatedVUs.Int64
	} else if carc.MaxVUs.Int64 < carc.PreAllocatedVUs.Int64 {
		errors = append(errors, fmt.Errorf("maxVUs can't be less than preAllocatedVUs"))
	}

	return errors

View on GitHub (pinned to 01ffac6f24)

Solutions

1. Increase duration to at least 100ms (e.g. '1s')
2. For very short tests consider the per-vu-iterations or shared-iterations executor instead

When it happens

Trigger: Thrown at lib/executor/constant_arrival_rate.go:106 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of grafana/k6@01ffac6f24 (2026-08-18). Data as JSON: /api/errors/593bff3ee9ae38c5. Report an issue: GitHub.