Build High Performance Asyncio Web Servers in Python

Mar 25, 2024 ยท 2 min read

Python's asyncio module allows you to write non-blocking, event-driven network code. This makes it possible to build very high performance web servers that can handle thousands of concurrent connections with very low resource usage.

Here's a simple asyncio web server example:

import asyncio

async def handle_request(reader, writer):
    request = await
    response = b"Hello World"
    await writer.drain()
async def main():
    server = await asyncio.start_server(handle_request, "", 8888)
    async with server:
        await server.serve_forever()

This handles each request in a separate coroutine, allowing it to serve multiple clients concurrently without blocking.

Tips for Building Asyncio Web Servers

  • Use an asynchronous web framework like Sanic, Quart, or FastAPI to reduce boilerplate code
  • Make sure to await long-running IO operations like reading requests/writing responses
  • Set a connection limit to avoid overloading resources with too many connections
  • Use serve_forever() to keep serving requests indefinitely
  • Catch exceptions properly to avoid crashing the server on errors
  • Challenges with Asyncio Servers

  • Debugging and testing async code can be more difficult due to its non-blocking nature
  • Scaling to multiple processes/servers is more complex than with sync servers
  • Async code can look confusing to those used to synchronous programming
  • Overall, asyncio allows you to achieve great performance improvements for network based applications in Python. With some care taken in understanding its asynchronous programming model, you can build very fast and efficient web services.

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