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192 Stars 21 Forks BSD 2-Clause "Simplified" License 89 Commits 3 Opened issues


Patch asyncio to allow nested event loops

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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


.. code-block::

pip3 install nest_asyncio

Python 3.5 or higher is required.


.. code-block:: python

import nest_asyncio

Optionally the specific loop that needs patching can be given as argument to

, 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.

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