POSIX Is Not a Shell

On December 16, 2024, a developer reported a bug in Trigger.dev, an open-source background job framework. A nightly server restart caused random tasks to remain in a queued state. The system's recovery logic repeatedly requeued these stalled tasks, resulting in 3,800 duplicate tasks. Although the monitoring system showed no errors and every task succeeded, the system continuously executed copies of work already completed, as the recovery process functioned exactly as designed without detecting the duplication.