⚡ Bolt: [performance improvement] Pre-serialized JSON caching for utility endpoints#616
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Implemented serialization caching in `get_leaderboard` and `get_stats` to improve response times. By serializing the output dictionaries to JSON strings before caching them, and returning a raw `fastapi.Response` with `media_type="application/json"`, we bypass the repetitive validation and JSON serialization overhead associated with `JSONResponse` on cache hits. Benchmark: - JSONResponse: ~1.5152s (10000 iterations) - Raw Response with pre-serialized JSON: ~0.0312s (10000 iterations)
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Pull request overview
Optimizes FastAPI utility endpoints by caching and returning pre-serialized JSON payloads to reduce per-request serialization overhead on cache hits.
Changes:
- Updated
/statsand/leaderboardto cache JSON strings and returnfastapi.Responsewithapplication/json. - Added a small benchmark script comparing
JSONResponsevs rawResponsewith pre-serialized JSON.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.
| File | Description |
|---|---|
| backend/routers/utility.py | Switches cached utility endpoints to return pre-serialized JSON via Response. |
| backend/tests/benchmark_serialization.py | Adds a benchmark script to measure serialization overhead differences. |
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Actionable comments posted: 2
🧹 Nitpick comments (1)
backend/routers/utility.py (1)
51-52: Add response-contract tests for/statsand/leaderboardendpoints.Both endpoints return
Responsedirectly (lines 55, 91, 121, 158), bypassing FastAPI's response-model validation. While the optimization is valid, contract tests should be added to lock and prevent regression of response shape and types (StatsResponseandLeaderboardResponse).🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed. In `@backend/routers/utility.py` around lines 51 - 52, Add response-contract tests that call the /stats and /leaderboard endpoints and validate the actual JSON response shape/types against the StatsResponse and LeaderboardResponse Pydantic models (e.g., by importing StatsResponse and LeaderboardResponse and using .parse_obj or model(**resp.json())). Specifically, write tests that exercise the get_stats (router path "/stats") and the leaderboard handler (router path "/leaderboard") which currently return fastapi.Response directly, fetch the endpoint JSON, and assert model parsing succeeds and required fields/types match; include negative/test-failure cases if keys are missing or types differ to lock the contract and prevent regressions. Ensure tests run in CI and mock DB/fixtures as needed so get_db-dependent handlers return stable predictable data.
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Inline comments:
In `@backend/routers/utility.py`:
- Around line 55-56: Cached cache hits from recent_issues_cache may be
non-string values causing malformed application/json responses; in the endpoints
that read cached_stats (and the other cached value around the referenced lines),
defensively check the cached value's type: if it's a str or bytes return it
directly, otherwise serialize the value to a JSON string (e.g., json.dumps)
before passing to Response with media_type="application/json"; update the code
paths that read from recent_issues_cache and the second cache read to perform
this type check/serialization so non-string Any values are handled safely.
In `@backend/tests/benchmark_serialization.py`:
- Around line 9-25: Rename the pytest-discovered functions test_jsonresponse and
test_rawresponse to names that won't be auto-collected (e.g., bench_jsonresponse
and bench_rawresponse or similar) and move the two print(...) calls so they only
run when the file is executed directly by wrapping them in an if __name__ ==
"__main__": guard; update any internal references to the renamed functions
accordingly so the benchmarks still run when invoked directly but are ignored by
pytest collection.
---
Nitpick comments:
In `@backend/routers/utility.py`:
- Around line 51-52: Add response-contract tests that call the /stats and
/leaderboard endpoints and validate the actual JSON response shape/types against
the StatsResponse and LeaderboardResponse Pydantic models (e.g., by importing
StatsResponse and LeaderboardResponse and using .parse_obj or
model(**resp.json())). Specifically, write tests that exercise the get_stats
(router path "/stats") and the leaderboard handler (router path "/leaderboard")
which currently return fastapi.Response directly, fetch the endpoint JSON, and
assert model parsing succeeds and required fields/types match; include
negative/test-failure cases if keys are missing or types differ to lock the
contract and prevent regressions. Ensure tests run in CI and mock DB/fixtures as
needed so get_db-dependent handlers return stable predictable data.
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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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💡 What: Optimized the caching logic in
get_leaderboardandget_statswithinbackend/routers/utility.pyto store pre-serialized JSON strings rather than Python dictionaries. It now returns a basefastapi.Responseinstead of aJSONResponse.🎯 Why: Storing raw dictionaries in the cache still required FastAPI/Pydantic to incur validation and serialization overhead on every cache hit. By caching the serialized string, we completely bypass this overhead.
📊 Impact: Expected performance improvement is significant for cache hits. Synthetic benchmarks show returning a raw response with pre-serialized JSON is approximately ~50x faster than passing dictionaries to
JSONResponse(0.0312s vs 1.5152s for 10000 iterations).🔬 Measurement: Verify by monitoring response latencies for the
/api/leaderboardand/api/statsendpoints, or by running the associated backend test suite.PR created automatically by Jules for task 568603064269904002 started by @RohanExploit
Summary by cubic
Optimized
/api/leaderboardand/api/statsby caching pre-serialized JSON and returning a rawfastapi.Response. This removes Pydantic/JSONResponseoverhead and lowers latency.json.dumpsand returnResponse(content=..., media_type="application/json")instead ofJSONResponsefor both endpoints (hits and misses).backend/tests/benchmark_serialization.py; shows ~50x speedup on 10k iterations (~1.5152s vs ~0.0312s).Written for commit 583c95d. Summary will update on new commits.
Summary by CodeRabbit
Refactor
/statsand/leaderboardnow return JSON payloads as application/json responses using pre-serialized JSON content.Tests