Making Asynchronous HTTP Requests in Python with aiohttp Connectors

The aiohttp library is a powerful tool for making asynchronous HTTP requests in Python. One key component is the aiohttp.TCPConnector, which manages the connection pooling for HTTP and HTTPS requests.

Why Use a Connector?

By default, every HTTP request will open a new TCP connection. This can be inefficient, as opening connections has overhead and latency.

A connector allows request calls to reuse open connections from a pool, avoiding new connections where possible. This improves performance.

Key Connector Options

Here are some key options to configure on a TCPConnector:

For example, here is how to create a connector with customized options:

connector = aiohttp.TCPConnector(
    limit=200, 
    limit_per_host=20,
    enable_cleanup_closed=True)  

And then we can pass it when creating a client session:

async with aiohttp.ClientSession(connector=connector) as session:
    ... # Make requests using this session

Tuning Timeouts

The connector also manages timeouts - like keepalive_timeout to close idle connections, and connect_timeout for initial connection establishment.

Tuning these and other options can optimize performance for your specific HTTP workloads.

Conclusion

The aiohttp.TCPConnector manages performant connection pooling and reuse in aiohttp. Tuning its options like limits, cleanups, and timeouts is key to optimizing asynchronous IO performance. Careful connector configuration can lead to faster and more robust HTTP clients and services in Python.