Asyncio events

Asyncio is a powerful feature in Python that allows you to write asynchronous, non-blocking code. This means your program can perform multiple tasks concurrently without getting blocked.

The key concept in asyncio is the event loop. This is like a central hub that manages all the asynchronous tasks. Here's a quick example:

import asyncio

async def my_task(x):
    print(f'Processing {x}')
    await asyncio.sleep(1)
    print(f'Done with {x}')

async def main():
    await asyncio.gather(
        my_task(1),
        my_task(2),
        my_task(3),  
    )

asyncio.run(main())

This schedules three instances of my_task() to run concurrently. While one task is waiting on the asyncio.sleep(), the event loop can switch to another ready task.

The key things that enable this asynchronous behavior are:

The async/await syntax - this marks a function as a coroutine that can be awaited

Coroutine functions like asyncio.sleep() that yield control back to the event loop

asyncio.run() which runs the event loop

Practical Examples

Asyncio works great for I/O bound use cases like:

Web scraping - await responses instead of blocking on requests

Network programming - handle many concurrent connections

Database access - await queries instead of waiting idly

It doesn't help much for CPU heavy tasks since there is still a single thread.

Challenges

Some challenges with async code:

Increased complexity from non-linear program flow

Race conditions and bugs from shared mutable state

Care required for clean shutdowns

Overall asyncio enables more responsive programs. With some care around design, it's a valuable tool for building high performance Python applications.

Practical Examples

Challenges

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Asyncio events

Practical Examples

Challenges

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