---
id: portalocker
version: "4.1.0"
license: BSD-3-Clause
license_treatment: permissive
maintenance: active
---

# portalocker — Cross-platform file locking, with Redis, PID-file and bounded-semaphore locks

License: permissive · Maintenance: active · Popularity: top 1,000 on PyPI

## Install

pip install portalocker
uv add portalocker
poetry add portalocker

## Description

############################################
portalocker - Cross-platform locking library
############################################

.. image:: https://github.com/wolph/portalocker/actions/workflows/ci.yml/badge.svg?branch=develop
    :alt: CI Test Status
    :target: https://github.com/wolph/portalocker/actions/workflows/ci.yml

Overview
--------

Portalocker is a library to provide an easy API to file locking.

Portalocker requires Python 3.10 or later.

An important detail to note is that on Linux and Unix systems the locks are
advisory by default. By specifying the `-o mand` option to the mount command it
is possible to enable mandatory file locking on Linux. This is generally not
recommended however. For more information about the subject:

 - https://en.wikipedia.org/wiki/File_locking
 - http://stackoverflow.com/questions/39292051/portalocker-does-not-seem-to-lock
 - https://stackoverflow.com/questions/12062466/mandatory-file-lock-on-linux

Windows and the ``pywin32`` dependency
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Since version 4.0.0, ``pywin32`` is no longer installed automatically on
Windows. Exclusive locks work out of the box without any extra
dependencies...

## AI interpretation — verify before relying

portalocker provides cross-platform file locking with an easy API, supporting exclusive and shared locks on Windows, Linux, Unix, and macOS, plus optional Redis-based distributed locks and PID-file locking for singleton patterns.

Verdict: portalocker is a mature, actively maintained library with zero known vulnerabilities, low install friction, and permissive licensing. It is well-suited for applications needing cross-platform file locking or distributed locks via Redis. The Python 3.10+ requirement and optional Windows dependency for shared locks are the only considerations.

[View on SkillFed](https://skillfed.io/packages/portalocker) · [View on PyPI](https://pypi.org/project/portalocker/)