How to Use await in Python: Simple Async Await Guide

In Python, use await inside an async function to pause execution until an asynchronous operation completes. This lets your program handle other tasks while waiting, improving efficiency.

Syntax

The await keyword is used inside an async function to pause its execution until the awaited asynchronous operation finishes. The basic syntax is:

• async def: declares an asynchronous function.
• await: pauses the function until the awaited coroutine or async task completes.

python

async def my_function():
    result = await some_async_operation()
    return result

Example

This example shows how to use await to pause an async function while waiting for a simulated delay, then print the result.

python

import asyncio

async def say_hello():
    print('Waiting...')
    await asyncio.sleep(2)  # Pause here for 2 seconds
    print('Hello after 2 seconds!')

asyncio.run(say_hello())

Output

Waiting...
Hello after 2 seconds!

Common Pitfalls

Common mistakes when using await include:

• Using await outside an async function causes a syntax error.
• Not running the async function properly with asyncio.run() or an event loop.
• Forgetting that await only works with awaitable objects like coroutines or tasks.

python

import asyncio

# Wrong: await outside async function
# await asyncio.sleep(1)  # SyntaxError

# Right way:
async def correct():
    await asyncio.sleep(1)

asyncio.run(correct())

Quick Reference

Remember these tips when using await in Python:

• Only use await inside async def functions.
• Use asyncio.run() to start your async functions from regular code.
• await pauses the function but does not block the whole program.

Key Takeaways

Use await only inside async functions to pause until async tasks finish.

Start async functions with asyncio.run() to run them properly.

await improves efficiency by letting other tasks run while waiting.

You cannot use await in regular (non-async) functions.

Only await awaitable objects like coroutines or tasks.