This post is a study dump. I’ve been reading ‘Access Path Selection in a Relational Database Management System’ (Selinger et al., 1979) and stopped at chapter 3 to consolidate what I learned.

A configuration flag changed. A boolean. The side effect opened a database connection pool before fork() and took down every Celery worker in production. This is an account of the investigation, the OS internals behind it, and a proposed solution still waiting for staging validation.