Reject work when the bounded queue is full
Producers append without limit while workers are paused, and the process consumes all available memory.
- Focused work estimate
- 1h 30m + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Backpressure · API design
Estimated field mix
- Systems programming70%
- 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
A fictional image-indexing utility runs CPU-only synthetic jobs through a Rust worker pool. Its prototype loses wakeups, blocks shutdown, and treats cancellation as completion. Build a local library and deterministic concurrency harness; image content, GPU work, and production deployment are excluded.
Setup prerequisites
- Mutexes and condition variables
- Atomics
- Thread lifecycle
Preceding work
No earlier ticket is required. Complete the project setup above.
Acceptance criteria
- Capacity is explicit and positive
- Submission returns accepted, timed out, or closed
- A rejected job remains caller-owned
Implementation constraints
- Do not hide backpressure behind an unbounded overflow list.
Verification to include
- Fill the queue, release one slot, and submit the next job.
- Keep workers paused and confirm memory and queue length remain bounded.
Deliverables
- Bounded submission API and overload tests
Rollout and recovery
Start with conservative capacity and surface rejections to the local caller.
Value of the work
For the engineer: Practice happens-before reasoning, ownership transfer, cancellation and liveness testing.
For the team: Review a worker primitive whose overload and shutdown behavior are predictable before it supports build or media workloads.
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.