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AsyncIO in Python

 


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AsyncIO in Python

AsyncIO is a library to write concurrent code using the async/await syntax. It allows you to manage asynchronous tasks and I/O operations in Python.

Basics of AsyncIO

AsyncIO provides an event loop, coroutines, and tasks:

  • Event loop: The core of every asyncio application. It runs asynchronous tasks and callbacks.
  • Coroutines: Special functions defined with async def. They use await to pause their execution and wait for other coroutines.
  • Tasks: Used to schedule coroutines to run concurrently in the event loop.
Creating a Simple Coroutine

import asyncio

# Define a coroutine
async def say_hello():
    print("Hello")
    await asyncio.sleep(1)
    print("World")

# Create an event loop and run the coroutine
asyncio.run(say_hello())
Running Multiple Coroutines

import asyncio

async def task1():
    await asyncio.sleep(1)
    print('Task 1 complete')

async def task2():
    await asyncio.sleep(2)
    print('Task 2 complete')

async def main():
    await asyncio.gather(task1(), task2())

asyncio.run(main())
Handling Timeouts

import asyncio

async def long_running_task():
    await asyncio.sleep(5)
    print("Task complete")

async def main():
    try:
        await asyncio.wait_for(long_running_task(), 3)
    except asyncio.TimeoutError:
        print("Task timed out")

asyncio.run(main())
Creating and Using Tasks

import asyncio

async def task1():
    await asyncio.sleep(1)
    print('Task 1 complete')

async def task2():
    await asyncio.sleep(2)
    print('Task 2 complete')

async def main():
    t1 = asyncio.create_task(task1())
    t2 = asyncio.create_task(task2())
    
    await t1
    await t2

asyncio.run(main())
Async Context Managers

import asyncio

class AsyncContextManager:
    async def __aenter__(self):
        print("Entering context")
        return self

    async def __aexit__(self, exc_type, exc, tb):
        print("Exiting context")

async def main():
    async with AsyncContextManager():
        print("Inside context")

asyncio.run(main())
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