aiohttp: set maximum number of requests per second

Question

How can I set maximum number of requests per second (limit them) in client side using aiohttp?

Answer 1

Since v2.0, when using a ClientSession, aiohttp automatically limits the number of simultaneous connections to 100.

You can modify the limit by creating your own TCPConnector and passing it into the ClientSession. For instance, to create a client limited to 50 simultaneous requests:

import aiohttp

connector = aiohttp.TCPConnector(limit=50)
client = aiohttp.ClientSession(connector=connector)

In case it's better suited to your use case, there is also a limit_per_host parameter (which is off by default) that you can pass to limit the number of simultaneous connections to the same "endpoint". Per the docs:

limit_per_host (int) – limit for simultaneous connections to the same endpoint. Endpoints are the same if they are have equal (host, port, is_ssl) triple.

Example usage:

import aiohttp

connector = aiohttp.TCPConnector(limit_per_host=50)
client = aiohttp.ClientSession(connector=connector)