---
id: nest-asyncio
version: "1.6.0"
license: BSD
license_treatment: permissive
maintenance: abandoned
---

# nest-asyncio — Patch asyncio to allow nested event loops

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

## Install

pip install nest-asyncio
uv add nest-asyncio
poetry add nest-asyncio

## Description

|Build| |Status| |PyPiVersion| |License| |Downloads|

Introduction
------------

By design asyncio `does not allow <https://github.com/python/cpython/issues/66435>`_
its event loop to be nested. This presents a practical problem:
When in an environment where the event loop is
already running it's impossible to run tasks and wait
for the result. Trying to do so will give the error
"``RuntimeError: This event loop is already running``".

The issue pops up in various environments, such as web servers,
GUI applications and in Jupyter notebooks.

This module patches asyncio to allow nested use of ``asyncio.run`` and
``loop.run_until_complete``.

Installation
------------

.. code-block::

    pip3 install nest_asyncio

Python 3.5 or higher is required.

Usage
-----

.. code-block:: python

    import nest_asyncio
    nest_asyncio.apply()

Optionally the specific loop that needs patching can be given
as argument to ``apply``, otherwise the current event loop is used.
An event loop can be patched whether it is already running
or not. Only event loops from asyncio can be patched;
Loops from other projects, such as uvloop or quamash,
generally can't be patched.


.. |Build| image::...

## AI interpretation — verify before relying

Patches asyncio to allow nested event loops, enabling asyncio.run() and loop.run_until_complete() to work in environments where an event loop is already running, such as Jupyter notebooks and web servers.

Verdict: nest_asyncio solves a real problem for running asyncio code in nested contexts with zero dependencies and a permissive license. However, the repository is archived and abandoned since early 2024, leaving no path for maintenance if future Python versions break compatibility or introduce new asyncio internals. Use only if your Python version and asyncio implementation are stable and unlikely to change.

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