Three application servers each running the same crontab means every scheduled task runs three times, and the invoice job discovers this before you do. The lock is a…
A PHP controller returns whatever the framework will serialise and the status code is set separately, which is why every codebase grows its own response helper. The return…
A one-gigabyte VPS running MySQL, PHP and nginx has no headroom, and the kernel resolves that by killing the largest process — which is MySQL, mid-write. Swappiness at…
8.0 defaults to utf8mb4_0900_ai_ci, which sorts and compares differently from the utf8mb4_general_ci a 5.7 database is almost certainly using — and a join between two columns with different…
Merely loading the extension slows execution substantially even with no debugging session and no profiler running, because it installs hooks into the engine. It ends up in production…
Jobs in the same stage run in parallel and jobs in later stages wait for all of the previous stage, which is obvious once stated and produces surprising…