chore(benchmarks): remove batched-loop sampling noise

[BridgeAR]

Criterion times output collection inside batched loops. The glob matcher and sampler benchmarks used that API with an empty setup, which made harness bookkeeping part of their short measurements.

On Apple Silicon with Rust 1.87.0, ten fresh-process measurements of the worst wildcard case narrowed from a 10.4-19.2 ns non-outlier range to 10.7-12.5 ns. The remaining outlier fell from 80.1 ns to 27.4 ns.

[datadog-datadog-prod-us1]

✅ All CI checks and tests passed.

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 77.74% (-0.03%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: c765273 | Docs | View more details | Give us feedback!}

[pr-commenter]

Benchmarks

Comparison

Benchmark execution time: 2026-09-14 11:27:43

Comparing candidate commit c765273 in PR branch BridgeAR/2026-09-09-benchmark-stability with baseline commit 1413485 in branch main.

📊 Benchmarking dashboard

Found 0 performance improvements and 5 performance regressions! Performance is the same for 43 metrics, 10 unstable metrics.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

• 🟩 = significantly better candidate vs. baseline
• 🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

scenario:glob_matcher/ascii_case_insensitive_match/wall_time

• 🟥 execution_time [+1.190ns; +1.206ns] or [+4.215%; +4.272%]

scenario:glob_matcher/ascii_exact_match/wall_time

• 🟥 execution_time [+1.144ns; +1.266ns] or [+4.041%; +4.471%]

scenario:glob_matcher/ascii_exact_miss/wall_time

• 🟥 execution_time [+1.210ns; +1.245ns] or [+9.041%; +9.302%]

scenario:glob_matcher/star_short_circuit/wall_time

• 🟥 execution_time [+0.629ns; +0.641ns] or [+15.032%; +15.316%]

scenario:glob_matcher/unicode_pattern_ascii_subject/wall_time

• 🟥 execution_time [+4.450ns; +4.532ns] or [+4.909%; +4.999%]

Unstable benchmarks

These benchmarks have a confidence interval too wide to call a change; treat them as noise rather than signal.

scenario:datadog_sample_span/parent_not_sampled_short_circuit/allocated_bytes

• unstable execution_time [-0.000ns; +0.000ns] or [+553.426%; -554.649%]

scenario:datadog_sample_span/parent_sampled_short_circuit/allocated_bytes

• unstable execution_time [-0.000ns; +0.000ns] or [+555.350%; -555.553%]

scenario:glob_matcher/ascii_case_insensitive_match/allocated_bytes

• unstable execution_time [-0.000ns; +0.000ns] or [+549.792%; -552.947%]

scenario:glob_matcher/ascii_exact_match/allocated_bytes

• unstable execution_time [-0.000ns; +0.000ns] or [+587.305%; -570.835%]

scenario:glob_matcher/ascii_exact_miss/allocated_bytes

• unstable execution_time [-0.000ns; +0.000ns] or [+554.874%; -555.330%]

scenario:glob_matcher/ascii_wildcard_backtrack_match/allocated_bytes

• unstable execution_time [-0.000ns; +0.000ns] or [+564.412%; -559.838%]

scenario:glob_matcher/ascii_wildcard_heavy_backtrack/allocated_bytes

• unstable execution_time [-0.000ns; +0.000ns] or [+559.176%; -557.357%]

scenario:glob_matcher/ascii_wildcard_question_match/allocated_bytes

• unstable execution_time [-0.000ns; +0.000ns] or [+558.843%; -557.200%]

scenario:glob_matcher/ascii_wildcard_star_match/allocated_bytes

• unstable execution_time [-0.000ns; +0.000ns] or [+559.621%; -557.568%]

scenario:glob_matcher/star_short_circuit/allocated_bytes

• unstable execution_time [-0.000ns; +0.000ns] or [+606.429%; -580.191%]

Candidate

Omitted due to size.

Baseline

Omitted due to size.

[dd-octo-sts]

Artifact Size Benchmark Report

aarch64-alpine-linux-musl

Artifact	Baseline	Commit	Change
/aarch64-alpine-linux-musl/lib/libdatadog_profiling.a	96.01 MB	96.01 MB	0% (0 B) 👌
/aarch64-alpine-linux-musl/lib/libdatadog_profiling.so	9.02 MB	9.02 MB	0% (0 B) 👌

aarch64-unknown-linux-gnu

Artifact	Baseline	Commit	Change
/aarch64-unknown-linux-gnu/lib/libdatadog_profiling.a	107.42 MB	107.42 MB	0% (0 B) 👌
/aarch64-unknown-linux-gnu/lib/libdatadog_profiling.so	12.19 MB	12.19 MB	0% (0 B) 👌

libdatadog-x64-windows

Artifact	Baseline	Commit	Change
/libdatadog-x64-windows/debug/dynamic/datadog_profiling_ffi.dll	29.04 MB	29.04 MB	0% (0 B) 👌
/libdatadog-x64-windows/debug/dynamic/datadog_profiling_ffi.lib	96.08 KB	96.08 KB	0% (0 B) 👌
/libdatadog-x64-windows/debug/dynamic/datadog_profiling_ffi.pdb	191.76 MB	191.77 MB	+0% (+8.00 KB) 👌
/libdatadog-x64-windows/debug/static/datadog_profiling_ffi.lib	818.09 MB	818.09 MB	0% (0 B) 👌
/libdatadog-x64-windows/release/dynamic/datadog_profiling_ffi.dll	9.69 MB	9.69 MB	0% (0 B) 👌
/libdatadog-x64-windows/release/dynamic/datadog_profiling_ffi.lib	96.08 KB	96.08 KB	0% (0 B) 👌
/libdatadog-x64-windows/release/dynamic/datadog_profiling_ffi.pdb	27.51 MB	27.51 MB	0% (0 B) 👌
/libdatadog-x64-windows/release/static/datadog_profiling_ffi.lib	55.58 MB	55.58 MB	0% (0 B) 👌

libdatadog-x86-windows

Artifact	Baseline	Commit	Change
/libdatadog-x86-windows/debug/dynamic/datadog_profiling_ffi.dll	25.41 MB	25.41 MB	0% (0 B) 👌
/libdatadog-x86-windows/debug/dynamic/datadog_profiling_ffi.lib	97.58 KB	97.58 KB	0% (0 B) 👌
/libdatadog-x86-windows/debug/dynamic/datadog_profiling_ffi.pdb	197.13 MB	197.08 MB	--.02% (-56.00 KB) 💪
/libdatadog-x86-windows/debug/static/datadog_profiling_ffi.lib	800.38 MB	800.38 MB	0% (0 B) 👌
/libdatadog-x86-windows/release/dynamic/datadog_profiling_ffi.dll	7.51 MB	7.51 MB	0% (0 B) 👌
/libdatadog-x86-windows/release/dynamic/datadog_profiling_ffi.lib	97.58 KB	97.58 KB	0% (0 B) 👌
/libdatadog-x86-windows/release/dynamic/datadog_profiling_ffi.pdb	29.63 MB	29.63 MB	0% (0 B) 👌
/libdatadog-x86-windows/release/static/datadog_profiling_ffi.lib	52.55 MB	52.55 MB	0% (0 B) 👌

x86_64-alpine-linux-musl

Artifact	Baseline	Commit	Change
/x86_64-alpine-linux-musl/lib/libdatadog_profiling.a	85.97 MB	85.97 MB	0% (0 B) 👌
/x86_64-alpine-linux-musl/lib/libdatadog_profiling.so	10.03 MB	10.03 MB	0% (0 B) 👌

x86_64-unknown-linux-gnu

Artifact	Baseline	Commit	Change
/x86_64-unknown-linux-gnu/lib/libdatadog_profiling.a	101.85 MB	101.85 MB	0% (0 B) 👌
/x86_64-unknown-linux-gnu/lib/libdatadog_profiling.so	12.25 MB	12.25 MB	0% (0 B) 👌

[yannham]

LGTM. I don't know why iter_batched has been used without any setup code/init value, this doesn't make a lot of sense to me.

[BridgeAR]

/merge

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-09-14 11:09:20 UTC ℹ️ Start processing command /merge

---

2026-09-14 11:09:27 UTC ℹ️ MergeQueue: Pull request is not mergeable yet

It will be processed automatically as soon as GitHub reports it as mergeable. View in MergeQueue UI.

• Run /code blockers to see what is blocking it.
• Run /remove to cancel it.

---

2026-09-14 11:39:12 UTC ℹ️ MergeQueue: merge request added to the queue

The expected merge time in main is approximately 48m (p90).

---

2026-09-14 12:11:52 UTC ℹ️ MergeQueue: This merge request was merged