Prevent overlapping edge jobs that share one local resource
Cache refresh and cleanup run simultaneously and contend for the same fixture directory. Add scoped single-flight admission.
- Focused work estimate
- 3h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Concurrency · Resource management
Estimated field mix
- Embedded and edge70%
- Performance engineering30%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
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Project context
Fictional kiosk software schedules cache refresh and display housekeeping. Build a software clock and job adapter; do not control real machinery or purchase hardware.
Setup prerequisites
- Implement injected wall and monotonic clocks.
- Create synthetic jobs with controllable completion and failure.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Same resource runs one job
- Different resources remain independent
- Failure releases admission
Implementation constraints
- Do not introduce an unbounded global waiting queue.
Verification to include
- Run separate resources
- Fail holder while another waits
Deliverables
- Resource admission and cases
Rollout and recovery
Serialize all fixture maintenance temporarily if scoped locking fails.
Value of the work
For the engineer: Practice timer semantics, cancellation and bounded scheduling.
For the team: Inspect predictable edge resource use and honest execution status.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.