thanos-io/thanos · error

invalid factor

Error message

invalid factor

What it means

The bucket growth factor in NewBucketedPool must be >= 1. Each bucket size is computed by multiplying the previous size by factor until maxSize; a factor < 1 would shrink toward zero and generate an invalid/degenerate bucket ladder.

Solutions

1. Pass a factor >= 1; use 2 for doubling (common default)
2. If a percentage was intended, convert it: factor = 1 + pct/100
3. Validate the config value before constructing the pool

Example fix

// before
pool, err := pool.NewBucketedPool[byte](1<<10, 1<<22, 0.5, 0)
// after
pool, err := pool.NewBucketedPool[byte](1<<10, 1<<22, 2.0, 0)

if factor < 1 {
    return errors.New("pool growth factor must be >= 1")
}
pool, err := pool.NewBucketedPool[byte](minSize, maxSize, factor, maxTotal)

p, err := pool.NewBucketedPool[byte](minSize, maxSize, factor, maxTotal)
if err != nil {
    return fmt.Errorf("configuring chunk pool: %w", err)
}

When it happens

Trigger: NewBucketedPool[T](minSize, maxSize, 0.5, maxTotal) or factor 0 / negative, usually from a misread config option for pool growth.

Common situations: Tuning pool memory by setting a fractional 'growth' value; copy-paste of factor as percentage 0.5 intending 1.5 or 2.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• invalid minimum pool size
• invalid maximum pool size
• parse limit configuration
• --receive.lazy-retrieval-max-buffered-responses must be > 0
• found that Prometheus and Thanos use different paths for…

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/0c0a535021515bb9. Report an issue: GitHub.

Appendix: source

Thrown at pkg/pool/pool.go:65

	if err != nil {
		panic(err)
	}
	return pool
}

// NewBucketedPool returns a new BucketedPool with size buckets for minSize to
// maxSize increasing by the given factor and maximum number of used items. No
// more than maxTotal items can be used at any given time unless maxTotal is set
// to 0.
func NewBucketedPool[T any](minSize, maxSize int, factor float64, maxTotal uint64) (*BucketedPool[T], error) {
	if minSize < 1 {
		return nil, errors.New("invalid minimum pool size")
	}
	if maxSize < 1 {
		return nil, errors.New("invalid maximum pool size")
	}
	if factor < 1 {
		return nil, errors.New("invalid factor")
	}

	var sizes []int

	for s := minSize; s <= maxSize; s = int(float64(s) * factor) {
		sizes = append(sizes, s)
	}
	p := &BucketedPool[T]{
		buckets:  make([]sync.Pool, len(sizes)),
		sizes:    sizes,
		maxTotal: maxTotal,
		new: func(sz int) *[]T {
			s := make([]T, 0, sz)
			return &s
		},
	}
	return p, nil
}

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