experimental/sources/: nest-asyncio-1.6.0 metadata and description

Homepage Simple index

Patch asyncio to allow nested event loops

author Ewald R. de Wit
author_email ewald.de.wit@gmail.com
  • Development Status :: 5 - Production/Stable
  • Intended Audience :: Developers
  • License :: OSI Approved :: BSD License
  • Programming Language :: Python :: 3.5
  • Programming Language :: Python :: 3.6
  • Programming Language :: Python :: 3.7
  • Programming Language :: Python :: 3.8
  • Programming Language :: Python :: 3.9
  • Programming Language :: Python :: 3.10
  • Programming Language :: Python :: 3.11
  • Programming Language :: Python :: 3.12
  • Programming Language :: Python :: 3 :: Only
  • Framework :: AsyncIO
description_content_type text/x-rst
keywords asyncio,nested,eventloop
license BSD
requires_python >=3.5
File Tox results History
7 KB

Build PyPi Number of downloads


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.


pip3 install nest_asyncio

Python 3.5 or higher is required.


import nest_asyncio

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.