What is the event loop?

The event loop is the “engine” that:

• runs coroutines
• pauses them at await points
• resumes them when I/O is ready

asyncio.run

asyncio.run(coro)asyncio.run(coro):

• creates an event loop
• runs the coroutine until complete
• closes the loop

import asyncio
 
 
async def main():
    await asyncio.sleep(0.1)
    return 123
 
 
print(asyncio.run(main()))

import asyncio
 
 
async def main():
    await asyncio.sleep(0.1)
    return 123
 
 
print(asyncio.run(main()))

Running multiple coroutines

To run multiple coroutines concurrently, you’ll use:

• tasks
• gather

(covered in next pages)

Common mistake in notebooks

Some notebook environments already have an event loop running.

If asyncio.runasyncio.run fails there, use notebook-safe patterns.

In normal Python scripts, prefer asyncio.runasyncio.run.

🧪 Try It Yourself

Exercise 1 – asyncio.run() Entry Point

Exercise 2 – Get the Running Loop

Exercise 3 – Schedule and Await