Important

This repo contains a fork of the original nest_asyncio package, which is no longer maintained as its author has passed away. 🌷

At this moment, this fork is not published at PyPI in any form.

Notable changes from original code:

• Added support for Python 3.14
• Dropped support for old Python versions, minimum supported version is now 3.9.
• Removed code for patching tornado asyncio loop.

Introduction

By design asyncio does not allow 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

$ pip3 install nest_asyncio

Python 3.9 or higher is required.

Usage

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.

Important

Only event loops from asyncio can be patched; loops from other projects, such as uvloop or quamash, generally can't be patched.