min_ring_size value of

Error message

min_ring_size value of %d is greater than max supported value %d for this field

What it means

Returned by ringhash's parseConfig() (balancer/ringhash/config.go:43) when MinRingSize exceeds ringHashSizeUpperBound (8 * 1024 * 1024 = 8388608). The ring is an in-memory hash ring of SubConn entries; an enormous ring would consume excessive memory, so it is hard-capped at 8M entries.

Solutions

Set minRingSize to a value <= 8388608 (8M).
Use the defaults (defaultMinSize = 1024) unless you have a measured need for more.
Prefer maxRingSize tuning over inflating minRingSize.

Example fix

// before: minRingSize beyond the hard cap
grpc.WithDefaultServiceConfig(`{"loadBalancingConfig":[{"ring_hash_experimental":{"minRingSize":100000000}}]}`)

// after: within the supported range (or omit for default 1024)
grpc.WithDefaultServiceConfig(`{"loadBalancingConfig":[{"ring_hash_experimental":{"minRingSize":1024,"maxRingSize":4096}}]}`)

Defensive patterns

Strategy: validation

Validate before calling

const ringHashUpperBound = 8 * 1024 * 1024
func validateMinRingSize(min uint64) error {
    if min > ringHashUpperBound {
        return fmt.Errorf("minRingSize %d exceeds max %d", min, ringHashUpperBound)
    }
    return nil
}

Prevention

Cap minRingSize at 8388608 in config generation / xDS policy validators.
Prefer defaults unless you have measured the need for a larger ring.

When it happens

Trigger: The ring_hash_experimental config sets minRingSize to a value > 8388608. json.Unmarshal succeeds, then the check at line 42 fails.

Common situations: A very large minRingSize requested (e.g. from an xDS control plane) to maximize distribution accuracy without understanding the memory cost; a config typo adding extra zeros.

Related errors

AI-assisted analysis of grpc/grpc-go@0c51461d27 (2026-08-11). Data as JSON: /api/errors/82d0010d01d897f7. Report an issue: GitHub.

Appendix: source

Thrown at balancer/ringhash/config.go:43

	"google.golang.org/grpc/internal/envconfig"
	"google.golang.org/grpc/internal/metadata"
	iringhash "google.golang.org/grpc/internal/ringhash"
)

const (
	defaultMinSize         = 1024
	defaultMaxSize         = 4096
	ringHashSizeUpperBound = 8 * 1024 * 1024 // 8M
)

func parseConfig(c json.RawMessage) (*iringhash.LBConfig, error) {
	var cfg iringhash.LBConfig
	if err := json.Unmarshal(c, &cfg); err != nil {
		return nil, err
	}
	if cfg.MinRingSize > ringHashSizeUpperBound {
		return nil, fmt.Errorf("min_ring_size value of %d is greater than max supported value %d for this field", cfg.MinRingSize, ringHashSizeUpperBound)
	}
	if cfg.MaxRingSize > ringHashSizeUpperBound {
		return nil, fmt.Errorf("max_ring_size value of %d is greater than max supported value %d for this field", cfg.MaxRingSize, ringHashSizeUpperBound)
	}
	if cfg.MinRingSize == 0 {
		cfg.MinRingSize = defaultMinSize
	}
	if cfg.MaxRingSize == 0 {
		cfg.MaxRingSize = defaultMaxSize
	}
	if cfg.MinRingSize > cfg.MaxRingSize {
		return nil, fmt.Errorf("min %v is greater than max %v", cfg.MinRingSize, cfg.MaxRingSize)
	}
	if cfg.MinRingSize > envconfig.RingHashCap {
		cfg.MinRingSize = envconfig.RingHashCap
	}
	if cfg.MaxRingSize > envconfig.RingHashCap {
		cfg.MaxRingSize = envconfig.RingHashCap

View on GitHub (pinned to 0c51461d27)