in module urllib.request， function getproxies_environment （https://github.com/python/cpython/blob/main/Lib/urllib/request.py#L2493）

iterate over all environment variables twice

I made a test:

1. create 2500 environment variables
2. call and timing getproxies_environment()
3. the result is: getproxies_environment() take more than 50ms, which is a big overhead

so if there are many environment variables(like 10 thousands) in a machine, packages depend on function urllib.request.getproxies_environment (like requests does) shall be very slow

is 10 thousands environment variables reasonable？

yes it is, for example, in k8s cluster，kubelete may add a set of environment variables all Services(could be 10 thousands even 100 thousands), in purpose of service discovery

so would it be ok that getproxies_environment don't iterate over all environment variables?

Linked PRs

• gh-91539: Small performance improvement of urrlib.request.getproxies_environment() #108771