Show quote latency percentiles alongside rejected and timed-out requests
The dashboard median improves when the slowest requests time out and disappear from successful-response measurements.
- Focused work estimate
- 2h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Metrics · Latency distributions
Estimated field mix
- Performance engineering50%
- Site reliability30%
- Privacy engineering20%
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 freight broker sees slow quote responses at dispatch handover. The service looks healthy in average-latency charts, yet a few long requests occupy every worker. Build a small synthetic quote service and controlled dependency stub before taking implementation tickets.
Setup prerequisites
- Create a local quote endpoint and a deterministic carrier-price stub; no repository or dataset is supplied.
- Use synthetic routes and a fixed workload manifest. Record runtime, machine resources and instrumentation settings.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Report p50, p95 and p99 with sample counts for completed requests, and separate timeout, rejection and transport-error counts.
- State the observation window and histogram precision; do not average percentiles across workers.
- Keep route identifiers, customer IDs and quote payloads out of metric labels.
Implementation constraints
- Use bounded result-class labels and merge histogram counts before computing aggregate percentiles.
Verification to include
- Replay a fixture with known short, long and timed-out requests and reconcile all attempts.
- Compare merged-worker results with the same samples processed in one worker, within the declared histogram precision.
Deliverables
- Latency dashboard definition and aggregation regression fixture
Rollout and recovery
Run the new view beside the existing chart for the synthetic workload; keep raw counters if rendering is reverted.
Value of the work
For the engineer: Learn to distinguish queueing, dependency delay, CPU work and measurement mistakes using reproducible observations.
For the team: Produce a reviewable diagnosis and guarded changes that could guide a team investigating customer-visible latency.
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.