1) Describe the error and the expected behavior.
Tempest seems to be consuming too much memory when

• CA cert file is too big (e.g., 290 KiB)
• urllib3 1.26.x is used as a dependency [1][2]

Take a look at the attached graphs in the first comment. The issue is not present when urllib3 2.2.3 is used.

2) What OS did you run into the issue on?

• Ubuntu 22.04
• CentOS Stream 9

3) Specify the steps to reproduce the bug:
1. Install tempest
2. Make sure that tempest uses urllib3 1.26.x
3. Set identity.ca_certificates_file so that it points to a big ca_cert file
4. Run tempest (e.g., tempest run --smoke --concurrency=4)

It looks like the issue is related to HTTPConnections in PoolManager keeping the ca cert files in memory long after the test class finished its execution [3].

WIP ideas of how to fix this:

• Run clear() on PoolManagers in the tearDown() in test.py [4]
• Run clear() when new HTTPConnection is created [5]
• Wait for bump up to a newer version of urllib3.

[1] https://opendev.org/openstack/tempest/src/commit/a350e320b162abc42c4b5236b258e1e8742048d0/requirements.txt#L22
[2] https://opendev.org/openstack/requirements/src/commit/1daffb38e8d91ac33de84c850ba406bcec7a8aaa/upper-constraints.txt#L179
[3] https://opendev.org/openstack/tempest/src/branch/master/tempest/lib/common/http.py
[4] https://review.opendev.org/c/openstack/tempest/+/934979
[5] https://review.opendev.org/c/openstack/tempest/+/934980