Asyncio for Algorithmic Trading — Part 2

Tasks, Scheduling, and What Actually Runs

In Part 1, we introduced the core model:

• Coroutines are functions that can pause
• The event loop is the scheduler
• await is a yield point

Now we will see some practical examples.

How to Run the Examples (Quick Practical Note)¶

All examples below assume you have a main() coroutine and want to execute it.

If you’re running this in:

A normal .py script:

asyncio.run(main())

Jupyter notebook:

await main()

Jupyter already runs inside an active event loop, so asyncio.run() will fail there. We explain this in more details in the appendix — for now just remember:

Script → asyncio.run(main())

Jupyter → await main()

My examples assume Jupyter so I will use await main() .

Defining a Coroutine

import asyncio
async def some_coroutine():
    print("Started")
    await asyncio.sleep(1)
    print("Finished")

Important observations:

1. async def defines a coroutine function.
2. await marks a suspension point.