Async IO in Python with aiohttp

Mar 3, 2024 ยท 2 min read

Asynchronous programming has become increasingly popular in Python web development. The aiohttp library provides a simple yet powerful framework for writing asynchronous Python web apps and APIs.

Why Async IO?

Synchronous code executes line-by-line, blocking on I/O operations like network requests or file access. Async code allows other processing to continue while waiting on these operations, improving utilization of system resources.

For I/O bound apps like web servers, asyncio can lead to substantial performance gains over synchronous frameworks like Flask or Django.

Key Features of aiohttp

Some handy features of aiohttp:

  • Async request handling - aiohttp.web handles each request in a separate async task. No need to manage threads manually.
  • async def handle(request):
        name = request.match_info.get('name', "Anonymous")
        text = "Hello, " + name
        return web.Response(text=text)
    app = web.Application()
    app.add_routes([web.get('/', handle)])
  • WebSockets - WebSocket support is built-in for real-time communication.
  • REST API helpers - Tools like aiohttp.web.View streamline building REST APIs.
  • Middleware - Extend request processing pipeline with middleware like logging, security, etc.
  • Testing utilities - aiohttp.test_utils and integration with pytest-aiohttp facilitate testing.
  • When to Use aiohttp

    aiohttp shines for I/O bound services like web APIs, real-time apps, network clients, and backends for frontend JavaScript apps.

    For CPU intensive work like scientific computing or AI, asyncio may not help much. Stick to threads or processes.

    In Summary

    aiohttp brings the performance benefits of async I/O to Python web development while retaining a simple, Pythonic API. With Python 3.7+ support for async/await syntax, it's a great fit for modern web and networked application development.

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