preprocessed profile error processing call line: %w

Error message

preprocessed profile error processing call line: %w

What it means

Thrown when strconv.Atoi fails to parse the first field of the weight line (split[0]) as an integer. This field represents the call-site offset — the line number within the caller function where the call occurs. The %w wraps the strconv error (e.g. ErrSyntax or ErrRange).

Source

Thrown at src/cmd/internal/pgo/deserialize.go:77

		calleeName := scanner.Text()

		if !scanner.Scan() {
			if err := scanner.Err(); err != nil {
				return nil, fmt.Errorf("error reading preprocessed profile: %w", err)
			}
			return nil, fmt.Errorf("preprocessed profile entry missing weight")
		}
		readStr = scanner.Text()

		split := strings.Split(readStr, " ")

		if len(split) != 2 {
			return nil, fmt.Errorf("preprocessed profile entry got %v want 2 fields", split)
		}

		co, err := strconv.Atoi(split[0])
		if err != nil {
			return nil, fmt.Errorf("preprocessed profile error processing call line: %w", err)
		}

		edge := NamedCallEdge{
			CallerName:     callerName,
			CalleeName:     calleeName,
			CallSiteOffset: co,
		}

		weight, err := strconv.ParseInt(split[1], 10, 64)
		if err != nil {
			return nil, fmt.Errorf("preprocessed profile error processing call weight: %w", err)
		}

		if _, ok := d.NamedEdgeMap.Weight[edge]; ok {
			return nil, fmt.Errorf("preprocessed profile contains duplicate edge %+v", edge)
		}

		d.NamedEdgeMap.ByWeight = append(d.NamedEdgeMap.ByWeight, edge) // N.B. serialization is ordered.

View on GitHub (pinned to b6b368adc5)

Solutions

Regenerate the profile so call-site offsets are plain decimal integers (base 10).
Verify the field order is offset-then-weight, not weight-then-offset.
Check that no non-numeric characters leaked into the offset field.

Example fix

// Before (broken): "0x2a 1000"  (hex offset)
// After (fixed):  "42 1000"     (decimal offset)

Defensive patterns

Strategy: validation

Validate before calling

// Validate that the offset field is a decimal integer:
func validateOffsets(path string) error {
    data, err := os.ReadFile(path)
    if err != nil { return err }
    lines := strings.Split(strings.TrimRight(string(data), "\n"), "\n")
    for i := 2; i < len(lines); i += 3 {
        fields := strings.Split(lines[i], " ")
        if _, err := strconv.Atoi(fields[0]); err != nil {
            return fmt.Errorf("line %d: invalid offset %q: %w", i+1, fields[0], err)
        }
    }
    return nil
}

Prevention

Ensure the serializer emits decimal line numbers for offsets, not hex or symbolic names.
Validate offset fields are valid integers before deserialization.
Keep field order consistent: offset first, weight second.

When it happens

Trigger: split[0] contains a non-numeric string, a number with leading/trailing junk, an empty string, or a value that overflows int. The line was successfully split into 2 fields but the first field is not a valid base-10 integer.

Common situations: Profile generated by a tool that emitted symbolic or hex offsets instead of decimal line numbers. Also happens if the serialization swapped field order (weight first, offset second) or if the offset field contains a function-relative annotation like "+42".

Related errors

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/b606f56222ba006c. Report an issue: GitHub.