What it is
aiohttp is an asynchronous HTTP client/server framework for Python, built on top of asyncio for high-performance networking.
aiohttp allows asynchronous HTTP requests and building async web servers using Python’s asyncio. It supports request handling, middleware, routing, and websockets.
Installation
pip install aiohttpGetting started
The smallest useful thing you can do with it, and what each part means.
python
import aiohttp
import asyncio
async def fetch():
async with aiohttp.ClientSession() as session:
async with session.get('https://httpbin.org/get') as resp:
print(await resp.text())
asyncio.run(fetch())Advanced usage
Where the library earns its place over a simpler alternative.
python
from aiohttp import web
async def hello(request):
return web.Response(text='Hello, aiohttp!')
app = web.Application()
app.add_routes([web.get('/', hello)])
web.run_app(app)Errors and fixes
The failures you are most likely to hit, and what actually resolves them.
- aiohttp.ClientError
- Handle network exceptions when making HTTP requests asynchronously.
Best practices
- Use `async with` for client sessions to ensure proper cleanup.
- Avoid blocking code in async functions; use asyncio-compatible libraries.
- Leverage middlewares for authentication and logging.
Background
Why it exists, and what it was reacting to.
aiohttp was created to enable async HTTP requests and web servers in Python. It allows handling many connections concurrently, making it suitable for real-time web applications and APIs.