[not-matthias]

In walltime mode with Vitest 3 and 4, a bench declared outside a describe block reports ::<name> to the runner, while its results use <file>::<name>. The profile and the results end up under different URIs, so the benchmark gets no flamegraph.

WalltimeRunner.populateBenchmarkUris registered URI prefixes for nested suites only. A top-level bench belongs to the root file suite, so the prefix lookup returned an empty string. The root suite is now registered with the file path. Nested suites keep the same prefixes as before.

The new walltime.test.ts runs a top-level bench and a nested bench through the runner and checks the URIs passed to setExecutedBenchmark. Without the fix it gets ::top-level bench. The Vitest 3 and 4 examples also get a top-level bench, so CI covers this case.

The Vitest 5 provider builds its URIs from the test's file path and was not affected.

Refs COD-3984

[codspeed]

Merging this PR will regress 7 benchmarks

3 warnings, 1 note

⚠️ Walltime results may be unreliable

Some benchmarks used the Walltime instrument outside CodSpeed Macro Runners, which can make the results inconsistent.

Learn more about Macro Runners

See affected benchmarks

⚠️ 14 benchmarks are dominated by system calls

System calls cannot be simulated consistently and are left out of the measure. The reported value understates the real cost. Switch to the Walltime instrument to measure them.

Learn more about system calls

See affected benchmarks

⚠️ Base and head ran on different runner types

Some benchmarks with significant performance changes were compared across different runner types, so the changes might not come from the code. Run base and head on the same runner type, or use CodSpeed Macro Runners for more stable results.

Learn more about Macro Runners

Open the report in CodSpeed to investigate

ℹ️ 25 benchmarks have no flamegraph

The flamegraph wasn't generated: most of the time was spent in runtime internals, which would leave nothing useful to analyze.

See affected benchmarks

⚡ 14 improved benchmarks
❌ 7 regressed benchmarks
✅ 243 untouched benchmarks
🆕 6 new benchmarks
⏩ 56 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Walltime	short body	1.6 µs	1.9 µs	-14.91%
❌	Walltime	short body	1.6 µs	1.9 µs	-14.37%
❌	Walltime	switch 2	84 ns	96 ns	-12.5%
❌	Walltime	short body	1.7 µs	1.9 µs	-12.42%
❌	Walltime	short body	1.6 µs	1.9 µs	-12.26%
❌	CPU Simulation	iterative fibo 20	26 µs	29.6 µs	-12.11%
❌	Walltime	short body	1.7 µs	1.9 µs	-11.25%
⚡	CPU Simulation	wait 500ms	47.9 ms	28 ms	+71.5%
⚡	CPU Simulation	short body	243.8 µs	155.1 µs	+57.17%
⚡	CPU Simulation	short body	243.6 µs	155 µs	+57.11%
⚡	CPU Simulation	wait 1sec	83.7 ms	56.2 ms	+48.76%
⚡	CPU Simulation	wait 500ms	47.1 ms	36.3 ms	+29.84%
⚡	Walltime	test sync baz 10	144 ns	120 ns	+20%
⚡	CPU Simulation	wait 1sec	85.1 ms	71.7 ms	+18.64%
⚡	CPU Simulation	long body	640.8 µs	549.7 µs	+16.58%
⚡	CPU Simulation	long body	640.7 µs	550 µs	+16.5%
⚡	Walltime	switch 2	96 ns	84 ns	+14.29%
⚡	Walltime	test_recursive_cached_fibo_10	2.5 µs	2.2 µs	+13.98%
⚡	Walltime	switch 2	108 ns	96 ns	+12.5%
⚡	Walltime	test sync baz 100	240 ns	216 ns	+11.11%
...	...	...	...	...	...

ℹ️ Only the first 20 benchmarks are displayed. Go to the app to view all benchmarks.

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing cod-3984-fix-vitest-top-level-bench-uri (7208f24) with main (d15b97d)}

Footnotes

1. 56 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[greptile-apps]

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge.

Summary

Fixes missing file prefixes for top-level benchmark markers in Vitest 3 and 4 walltime runs.

• Top-level walltime benches use their file path in profile URIs.

No actionable issues found. Tests were not run.

_{Reviews (1) · Last reviewed commit: "fix(vitest-plugin): prefix walltime URIs..." · Reviewed by Greptile}