issue: 3782717 Improve Fairness for NGINX High Concurrency

[pasis]

Description

This is set of commit from the fairness activity. They're quality improvements that help in multi process statistics analysis and running XLIO on the client side on a big scale.

What

Quality improvements.

Why ?

Improvements and benchmark scenarios analysis.

Change type

What kind of change does this PR introduce?

• [ ] Bugfix
• [x] Feature
• [ ] Code style update
• [x] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [x] Documentation content changes
• [ ] Tests
• [ ] Other

Check list

• [ ] Code follows the style de facto guidelines of this project
• [ ] Comments have been inserted in hard to understand places
• [ ] Documentation has been updated (if necessary)
• [ ] Test has been added (if possible)