Check whether quote serialization is blocking unrelated requests
The largest multi-stop responses correlate with event-loop delay. The team has proposed adding workers before confirming where time is spent.
- Focused work estimate
- 2h 30m + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Profiling · Experimental design
Estimated field mix
- Performance engineering70%
- Backend30%
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
- Capture CPU and event-loop delay measurements for small and maximum-size synthetic quote responses.
- Separate JSON serialization cost from database and dependency time in the experiment.
- Produce a decision note identifying the measured bottleneck, uncertainty and one bounded next change; report when the hypothesis is unsupported.
Implementation constraints
- Use three repeated baseline runs after warmup on the same runtime and resource limits; save the measurement commands.
Verification to include
- Repeat with a prebuilt response body to isolate serialization while retaining the same payload size.
- Run a small health request concurrently and compare its tail latency with and without the large-response workload.
Deliverables
- Reproducible profiling report and supported next-step decision
Rollout and recovery
This investigation changes no serving path; retain the baseline commands for the implementation review.
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.