How do I run Python asyncio code in a Jupyter notebook?

This is no longer an issue in the latest jupyter release!

Just write an async function, and then await it directly in a jupyter cell.

async def fn():
  await asyncio.sleep(1)

await fn()

EDIT FEB 21st, 2019: Problem Fixed

This is no longer an issue on the latest version of Jupyter Notebook. Authors of Jupyter Notebook detailed the case here.

Answer below was the original response that was marked correct by the op.

This was posted quite a bit ago, but in case other people are looking for an explanation and solution to the problem of running asynchronous code inside Jupyter Notebook;

Jupyter's Tornado 5.0 update bricked asyncio functionalities after the addition of its own asyncio event loop:

Running on shell. Running on JupyterNotebook.

Thus, for any asyncio functionality to run on Jupyter Notebook you cannot invoke a loop.run_until_complete(...), since the loop you will receive from asyncio.get_event_loop() will be active.

Instead, you must either add the task to the current event loop:

import asyncio
loop = asyncio.get_event_loop()

Or get the results via run_coroutine_threadsafe:

import asyncio
loop = asyncio.get_event_loop()
asyncio.run_coroutine_threadsafe(some_async_function(), loop)