asyncio is a co-operative multitasking library available in Python since version 3.6. Celery is fantastic for running concurrent tasks out of a process, but there are certain times you will need to run multiple execution threads within the same process.

If you are not familiar with async/await concepts (say from JavaScript or C#), it involves a bit of a steep learning curve. However, it is well worth your time, as it can speed up your code tremendously (unless it is completely CPU-bound). Moreover, it helps in understanding other libraries built on top of them, such as Django Channels.

All asyncio programs are driven by an event loop, which is pretty much an infinite loop that calls all registered coroutines in some order. Each coroutine operates cooperatively by yielding control to fellow coroutines at well-defined places. This is called awaiting.

A coroutine is like a special function that can suspend and resume execution. It works in the same way as lightweight threads. Native coroutines use the async and await keywords, as follows:

import asyncio 
 
 
async def sleeper_coroutine(): 
    await asyncio.sleep(5) 
 
 
if __name__ == '__main__': 
    loop = asyncio.get_event_loop() 
    loop.run_until_complete(sleeper_coroutine()) 

This is a minimal example of an event loop running one coroutine named sleeper_coroutine. When invoked, this coroutine runs until the await statement and yields control back to the event loop. This is usually where an I/O activity occurs.

The control comes back to the coroutine at the same line when the activity being awaited is completed (after 5 seconds). Then, the coroutine returns or is considered completed.