Thinking in Systems

Up next, and overdue, because of a bug that was pure systems thinking and got debugged as if it were a code defect.

The janitor picked its next page at random from the pages that were dirty. A page a visitor was actively editing was reliably the dirtiest page, so it went back there every time — and the pages nobody had touched in an hour were never visited at all. No line of that was wrong. The feedback loop was.

The lever

The fix was not better code but a different input: weight the choice by how long since a page was last seen, not by how far it has drifted. One term, and the whole behaviour changed.