vitessio/vitess · error

invalid max replication lag config: %w

Error message

invalid max replication lag config: %w

What it means

newThrottlerFromConfig calls Verify() on the MaxReplicationLagModuleConfig before constructing the throttler and wraps any failure with 'invalid max replication lag config'. Throttler creation is aborted because the replication-lag module settings are invalid.

Source

Thrown at go/vt/throttler/throttler.go:163

func NewThrottler(name, unit string, threadCount int, maxRate, maxReplicationLag int64) (Throttler, error) {
	return newThrottler(GlobalManager, name, unit, threadCount, maxRate, maxReplicationLag, time.Now)
}

func NewThrottlerFromConfig(name, unit string, threadCount int, maxRateModuleMaxRate int64, maxReplicationLagModuleConfig MaxReplicationLagModuleConfig, nowFunc func() time.Time) (Throttler, error) {
	return newThrottlerFromConfig(GlobalManager, name, unit, threadCount, maxRateModuleMaxRate, maxReplicationLagModuleConfig, nowFunc)
}

func newThrottler(manager *managerImpl, name, unit string, threadCount int, maxRate, maxReplicationLag int64, nowFunc func() time.Time) (Throttler, error) {
	config := NewMaxReplicationLagModuleConfig(maxReplicationLag)
	config.MaxReplicationLagSec = maxReplicationLag

	return newThrottlerFromConfig(manager, name, unit, threadCount, maxRate, config, nowFunc)
}

func newThrottlerFromConfig(manager *managerImpl, name, unit string, threadCount int, maxRateModuleMaxRate int64, maxReplicationLagModuleConfig MaxReplicationLagModuleConfig, nowFunc func() time.Time) (Throttler, error) {
	err := maxReplicationLagModuleConfig.Verify()
	if err != nil {
		return nil, fmt.Errorf("invalid max replication lag config: %w", err)
	}
	if maxRateModuleMaxRate < 0 {
		return nil, fmt.Errorf("maxRate must be >= 0: %v", maxRateModuleMaxRate)
	}

	// Enable the configured modules.
	maxRateModule := NewMaxRateModule(maxRateModuleMaxRate)
	actualRateHistory := newAggregatedIntervalHistory(1024, 1*time.Second, threadCount)
	maxReplicationLagModule, err := NewMaxReplicationLagModule(maxReplicationLagModuleConfig, actualRateHistory, nowFunc)
	if err != nil {
		return nil, err
	}

	modules := make([]Module, 0, 2)
	modules = append(modules, maxRateModule)
	modules = append(modules, maxReplicationLagModule)

	// Start each module (which might start own Go routines).

View on GitHub (pinned to 01a25a7d17)

Solutions

1. Inspect the wrapped error (%w) to identify the exact invalid field.
2. Correct the max_replication_lag_module config values per Verify() constraints.
3. Call MaxReplicationLagModuleConfig.Verify() in your config-loading code before NewThrottlerFromConfig to fail fast.

Example fix

// before
config.TargetReplicationLagSec = 0
throttler.NewThrottlerFromConfig(mgr, name, unit, 1, 100, config, nowFunc)
// after
config.TargetReplicationLagSec = 1
config.MaxReplicationLagSec = 10
if err := config.Verify(); err != nil { return err }
throttler.NewThrottlerFromConfig(mgr, name, unit, 1, 100, config, nowFunc)

if err := cfg.Verify(); err != nil {
    return fmt.Errorf("invalid max replication lag config: %w", err)
}

t, err := throttler.NewThrottlerFromConfig(mgr, name, unit, threads, maxRate, cfg, nowFunc)
if err != nil {
    return vterrors.Wrapf(err, "creating throttler %s", name)
}

When it happens

Trigger: NewThrottlerFromConfig or newThrottler invoked with a config whose fields violate Verify() (target/max lag bounds, initial_rate < 1, non-positive max-increase, etc.).

Common situations: vreplication/vstreamer constructing a throttler from vtctld flags or topology-stored settings; a malformed --throttler-config-* flag or bad JSON in the topo.

Related errors

• invalid NewMaxReplicationLagModuleConfig: %v
• target_replication_lag_sec must not be higher than max_repli
• maxRate must be >= 0: %v
• ignoring higher good rate of %v because we assume that the k
• ignoring lower bad rate of %v because such a high degradatio

AI-assisted analysis of vitessio/vitess@01a25a7d17 (2026-09-01). Data as JSON: /api/errors/56b61ab6ff89fb1a. Report an issue: GitHub.