feat(otel): add OTel consistent probability sampling state to spans exported through OTLP

[vpellan]

Description

This is a follow up to #19751 and implements the same behaviour but on OTLP

Testing

Locally tested against DataDog/system-tests#7372 (tests/otel/test_tracing_otlp.py::Test_Otlp_**_Ot)
I will update the manifests once this is merged

Risks

Additional Notes

[datadog-datadog-prod-us1-2]

 

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⚠️ Warnings

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ℹ️ Info

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🧪 All tests passed
❄️ No new flaky tests detected

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[pr-commenter]

Benchmarks

Benchmark execution time: 2026-08-20 15:41:46

Comparing candidate commit faa25b0 in PR branch vpellan/otlp-th-rv-support with baseline commit d9fdb65 in branch main.

📊 Benchmarking dashboard

Found 0 performance improvements and 9 performance regressions! Performance is the same for 612 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:httppropagationinject-ids_only

• 🟥 execution_time [+2.121µs; +2.289µs] or [+11.043%; +11.920%]

scenario:iastaspects-casefold_noaspect

• 🟥 execution_time [+24.804µs; +32.281µs] or [+9.955%; +12.956%]

scenario:iastaspectsospath-ospathbasename_aspect

• 🟥 execution_time [+118.047µs; +124.479µs] or [+28.592%; +30.150%]

scenario:span-start

• 🟥 execution_time [+1.528ms; +1.667ms] or [+10.134%; +11.060%]

scenario:span-start-finish

• 🟥 execution_time [+4.457ms; +4.733ms] or [+8.075%; +8.575%]

scenario:span-start-finish-telemetry

• 🟥 execution_time [+4.739ms; +4.962ms] or [+8.636%; +9.041%]

scenario:span-start-finish-traceid128

• 🟥 execution_time [+4.543ms; +4.818ms] or [+7.906%; +8.386%]

scenario:telemetryaddmetric-1-count-metric-1-times

• 🟥 execution_time [+394.654ns; +441.519ns] or [+14.295%; +15.992%]

scenario:tracer-small

• 🟥 execution_time [+35.337µs; +37.895µs] or [+10.446%; +11.202%]

Unstable benchmarks

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

scenario:coreapiscenario-context_with_data_listeners

• unstable execution_time [-906.265ns; +586.677ns] or [-8.039%; +5.204%]

scenario:coreapiscenario-core_dispatch_1_listener

• unstable execution_time [-12.311ns; +57.933ns] or [-2.006%; +9.441%]

scenario:coreapiscenario-core_dispatch_50_listeners

• unstable execution_time [-1624.148ns; +1687.134ns] or [-9.519%; +9.888%]

scenario:coreapiscenario-core_dispatch_exception_listeners

• unstable execution_time [-1924.337ns; +621.354ns] or [-14.096%; +4.551%]

scenario:coreapiscenario-core_dispatch_listeners

• unstable execution_time [-322.042ns; +329.479ns] or [-8.694%; +8.895%]

scenario:coreapiscenario-core_dispatch_no_args_listeners

• unstable execution_time [-269.774ns; +242.926ns] or [-9.195%; +8.280%]

scenario:coreapiscenario-core_dispatch_with_results_1_listener

• unstable execution_time [-108.286ns; +44.670ns] or [-8.978%; +3.704%]

scenario:coreapiscenario-core_dispatch_with_results_50_listeners

• unstable execution_time [-4664.335ns; +3526.147ns] or [-11.240%; +8.497%]

scenario:coreapiscenario-core_dispatch_with_results_listeners

• unstable execution_time [-833.297ns; +699.684ns] or [-10.180%; +8.547%]

scenario:packagesupdateimporteddependencies-import_many_stdlib_cached

• unstable execution_time [-66.104µs; +56.701µs] or [-10.190%; +8.740%]