grpc/grpc-go · error

duplicated name

Error message

duplicated name

What it means

errDuplicatedName (service_config.go:129) is returned in a serviceconfig.ParseResult when two methodConfig entries in a service config resolve to the same /Service/Method path. gRPC requires each method path to appear at most once, so the parser records the duplicate as a parse error. The collision is detected at service_config.go:250-253.

Source

Thrown at service_config.go:129

	// between 0 and maxTokens.
	//
	// This field is required and must be greater than zero.
	MaxTokens float64
	// The amount of tokens to add on each successful RPC. Typically this will
	// be some number between 0 and 1, e.g., 0.1.
	//
	// This field is required and must be greater than zero. Up to 3 decimal
	// places are supported.
	TokenRatio float64
}

type jsonName struct {
	Service string
	Method  string
}

var (
	errDuplicatedName             = errors.New("duplicated name")
	errEmptyServiceNonEmptyMethod = errors.New("cannot combine empty 'service' and non-empty 'method'")
)

func (j jsonName) generatePath() (string, error) {
	if j.Service == "" {
		if j.Method != "" {
			return "", errEmptyServiceNonEmptyMethod
		}
		return "", nil
	}
	res := "/" + j.Service + "/"
	if j.Method != "" {
		res += j.Method
	}
	return res, nil
}

// TODO(lyuxuan): delete this struct after cleaning up old service config implementation.

View on GitHub (pinned to 03255a9237)

Solutions

1. Inspect the service config JSON and deduplicate methodConfig name entries so each /Service/Method path is unique.
2. If using a control plane, fix the policy generation logic that emits overlapping entries.
3. Validate the config with a schema/uniq check before publishing to service discovery.
4. Remove bare service-name entries that overlap explicit method entries.

Example fix

// before
{
  "methodConfig": [
    { "name": [{"service":"svc","method":"M"}], "retryPolicy": {...} },
    { "name": [{"service":"svc","method":"M"}], "retryPolicy": {...} }
  ]
}

// after - merge into one entry
{
  "methodConfig": [
    { "name": [{"service":"svc","method":"M"}], "retryPolicy": {...} }
  ]
}

func validateServiceConfig(raw []byte) error {
    var sc map[string]any
    if err := json.Unmarshal(raw, &sc); err != nil { return err }
    seen := map[string]bool{}
    for _, mc := range sc["methodConfig"].([]any) {
        for _, n := range mc.(map[string]any)["name"].([]any) {
            nm := n.(map[string]any)
            path := "/" + nm["service"].(string) + "/" + nm["method"].(string)
            if seen[path] { return fmt.Errorf("duplicate method %s", path) }
            seen[path] = true
        }
    }
    return nil
}

pr := scparser.Parse(raw)
if pr.Err != nil {
    if strings.Contains(pr.Err.Error(), "duplicated name") {
        log.Printf("service config has duplicate method: %v", pr.Err)
    }
}

When it happens

Trigger: A service config JSON whose methodConfig[].name lists the same service+method twice, or two name blocks that generate the same path (e.g. a bare service name matching an earlier service+method entry).

Common situations: Hand-edited service config with overlapping method rules; a control plane merging per-method policies that collide; renaming a service but leaving stale entries; wildcard/bare-name entries overlapping specific ones.

Related errors

• no error details for status with code OK
• rls: bad control channel service config %q: %v
• rls: stale_age is set, but max_age is not in route lookup co
• rls: cache_size_bytes must be set to a non-zero value: %+v
• rls: invalid childPolicy: entry %v does not contain exactly

AI-assisted analysis of grpc/grpc-go@03255a9237 (2026-08-07). Data as JSON: /api/errors/e079317ac14cae57. Report an issue: GitHub.