Stress testing HTTP with Twisted Python and Treq

Introducing Treq on Twisted

To solve this problem we looked at Treq (Github repository). Treq is an HTTP client library inspired by Requests, but it runs on Twisted and it possesses the typical Twisted powers: it is asynchronous and highly concurrent when it comes to network I/O.

Treq is not specific to stress testing at all: it’s a great tool for writing highly concurrent HTTP clients in general, like web crawlers. Treq is elegant, simple to use and powerful. Here’s an example:

The simple testing script

Below is a simple script which uses Treq to bombard a single URL with maximum possible number of requests.

The output:

The “Generated” ones are the requests that have been prepared, but the Twisted reactor has not sent them yet. This script ignores all errors for simplicity, adding the stats for timeouts is left as an exercise for the reader.

The script can be used as a starting point and improved and extended with your own custom application-specific logic. One suggested improvement would be to use collections.Counter instead of the ugly globals. The script runs on a single thread, and to squeeze the maximum number of requests from a machine something like mulitprocessing can be used.

Happy stress testing!

Cheers, Mailgunners