[Ubuntu] Can get parent from child, but not child from parent

[alex-wenzel]

Summary

• OS: Ubuntu Ubuntu 24.04.2 LTS
• Architecture: 64bit, x86
• Psutil version: 7.0.0
• Python version: 3.12.3
• Type: core

Description

Given a specific known parent/child pair, I get expected results from child.parent() but parent.child() does not contain the specific child.

I'm specifically looking at these Python processes:

As I think would be expected, the Python child process 6176 is actually a child of the sleeping bash process 1313, not its initiating Python process 6175. However, psutil is aware that 1313 is the parent of 6176, but not that 6176 is a child of 1313. I also checked and 6176 is not listed as a child of 6175 either.

[alex-wenzel]

After further investigation, I believe these children aren't found because they're actually threads and are related to 6175 by tgid as opposed to ppid (which is 1313).

It's not immediately clear to me from previous issues and documentation what expected behavior should be with respect to child threads, so I'll leave this issue open for now.