What causes "parent PID %d is invalid" in seaweedfs/seaweedfs?

Remove `-o child=...` entirely - the master process appends it automatically when spawning the child

parent PID %d is invalid

Error message

parent PID %d is invalid

What it means

The `child=<pid>` option marks this weed process as the child half of the FUSE daemonization pair: the master re-execs the weed binary with `-o child=<master PID>` appended (fuse_std.go:311). The value parses as a 64-bit decimal int, then this panic fires when it is <= 0 or exceeds math.MaxInt. The normal producer is strconv.Itoa(os.Getpid()), which can never emit such a value, so hitting this means the child= option was hand-crafted, copied, or corrupted.

Source

Thrown at weed/command/fuse_std.go:115

	}

	// get residual option data
	if option.Len() > 0 {
		// add value to pending option
		options = append(options, parameter{option.String(), "true"})
		option.Reset()
	}

	// scan each parameter
	for i := 0; i < len(options); i++ {
		parameter := options[i]

		switch parameter.name {
		case "child":
			masterProcess = false
			if parsed, err := strconv.ParseInt(parameter.value, 10, 64); err == nil {
				if parsed > math.MaxInt || parsed <= 0 {
					panic(fmt.Errorf("parent PID %d is invalid", parsed))
				}
				mountOptions.fuseCommandPid = int(parsed)
			} else {
				panic(fmt.Errorf("parent PID %s is invalid: %w", parameter.value, err))
			}
		case "arg0":
			mountOptions.dir = &parameter.value
		case "filer":
			mountOptions.filer = &parameter.value
		case "filer.path":
			mountOptions.filerMountRootPath = &parameter.value
		case "dirAutoCreate":
			if parsed, err := strconv.ParseBool(parameter.value); err == nil {
				mountOptions.dirAutoCreate = &parsed
			} else {
				panic(fmt.Errorf("dirAutoCreate: %s", err))
			}
		case "collection":

View on GitHub (pinned to 1c926e8fac)

Solutions

Remove `-o child=...` entirely - the master process appends it automatically when spawning the child
If you must simulate a child, pass a live positive decimal PID such as `-o child=1234`
Prefer `weed mount -dir=... -filer=...` which mounts directly and skips the master/child re-exec path
On 32-bit builds, confirm the PID fits in int32 (kernel pid_max caps at 4194304, so this is normally automatic)

Example fix

// before
weed fuse /mnt/sw -o "filer=localhost:8888,child=0"

// after
weed fuse /mnt/sw -o "filer=localhost:8888"
// child=<master pid> is appended automatically by the master process

Defensive patterns

Strategy: validation

Validate before calling

# bash: reject bogus child= values before invoking the helper
if [[ "$opts" =~ child=([^ ,]*) ]]; then
  pid="${BASH_REMATCH[1]}"
  [[ "$pid" =~ ^[1-9][0-9]*$ ]] || { echo "bad child pid: $pid" >&2; exit 1; }
fi

Type guard

func isValidChildPid(v string) bool {
	parsed, err := strconv.ParseInt(v, 10, 64)
	return err == nil && parsed > 0 && parsed <= int64(math.MaxInt)
}

Prevention

Never pass child= yourself; it is an internal option generated by the master process
When testing the child path, take the PID from the live master, not from stale ps output
Validate generated command lines in wrappers before exec

When it happens

Trigger: Invoking the fuse helper with an explicit `-o child=0` or `-o child=-5`; a 32-bit weed build receiving child=2500000000 (> MaxInt32); scripts that rebuild the master argv and mangle the PID field.

Common situations: Manually re-running the child command copied from `ps` output; systemd/wrapper units that rewrite argv; shell quoting bugs that truncate the value to 0.

Related errors

AI-assisted analysis of seaweedfs/seaweedfs@1c926e8fac (2026-08-15). Data as JSON: /api/errors/dd7912ea3cf578bf. Report an issue: GitHub.