pytest-dev/pytest · error · OSError

lock path got renamed after successful creation

Error message

lock path got renamed after successful creation

What it means

Raised by create_cleanup_lock after a lock file is successfully created and written, but is_found.is_file() returns False immediately after (lines 297-302). This detects a TOCTOU race where another process moved or removed the lock between creation and the existence check. It signals filesystem instability or concurrent cleanup interference.

Solutions

1. Point pytest's basetemp at a local, non-synced filesystem.
2. Avoid concurrent pytest runs sharing the same tmp root.
3. Exclude the tmp dir from sync/antivirus scanning.

Example fix

// before
pytest --basetemp=~/Dropbox/pytest
// after
pytest --basetemp=/tmp/pytest-run

import os
if any(sync in str(p) for sync in ['Dropbox', 'OneDrive', 'icloud']):
    raise RuntimeError('basetemp on a synced volume is unsafe')

def _on_local_fs(p) -> bool:
    import os
    return not any(s in str(p) for s in ('Dropbox', 'OneDrive', 'icloud'))

When it happens

Trigger: A concurrent cleanup process deletes or renames the lock right after creation; antivirus or sync software (Dropbox, OneDrive) moving newly created files; network filesystems with delayed visibility.

Common situations: Cloud-synced tmp directories; NFS with caching; concurrent pytest runs with overlapping cleanup windows.

Related errors

• could not create numbered dir with prefix
• cannot create lockfile in
• {path}
• Can't find module at location
• Could not resolve for

AI-assisted analysis of pytest-dev/pytest@0d6fbdeffa (2026-08-11). Data as JSON: /api/errors/64e5b38217ee42a1. Report an issue: GitHub.

Appendix: source

Thrown at src/_pytest/pathlib.py:302

            "could not create numbered dir with prefix "
            f"{prefix} in {root} after 10 tries"
        )


def create_cleanup_lock(p: Path) -> Path:
    """Create a lock to prevent premature directory cleanup."""
    lock_path = get_lock_path(p)
    try:
        fd = os.open(str(lock_path), os.O_WRONLY | os.O_CREAT | os.O_EXCL, 0o644)
    except FileExistsError as e:
        raise OSError(f"cannot create lockfile in {p}") from e
    else:
        pid = os.getpid()
        spid = str(pid).encode()
        os.write(fd, spid)
        os.close(fd)
        if not lock_path.is_file():
            raise OSError("lock path got renamed after successful creation")
        return lock_path


def register_cleanup_lock_removal(lock_path: Path, register: Any) -> Any:
    """Register a cleanup function for removing a lock."""
    pid = os.getpid()

    def cleanup_on_exit(lock_path: Path = lock_path, original_pid: int = pid) -> None:
        current_pid = os.getpid()
        if current_pid != original_pid:
            # fork
            return
        try:
            lock_path.unlink()
        except OSError:
            pass

    return register(cleanup_on_exit)

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