feat: OTel context sharing

[morrisonlevi]

Description

This adds OTel context sharing using libdatadog. It adds it to both tracing (producer) and profiling (consumer).

This is mostly AI-written with a little human review as I went. It is not ready for merge, but it did pass some local end-to-end experimentation.

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[datadog-datadog-prod-us1]

 

✨ Fix all issues with BitsAI

⚠️ Warnings

🚦 22 Pipeline jobs failed

DataDog/apm-reliability/dd-trace-php | appsec integration tests: [test8.4-release]     

🧪 1 Test failed

All test failures are known flaky.

❄️ Known flaky: extended heartbeat re-emits configuration, dependencies and integrations() from com.datadog.appsec.php.integration.TelemetryExtendedHeartbeatTests  

java.lang.AssertionError: phpredis not emitted via app-started/app-integrations-change; saw: []. Expression: (phpredis in flushed). Values: flushed = []

java.lang.AssertionError: phpredis not emitted via app-started/app-integrations-change; saw: []. Expression: (phpredis in flushed). Values: flushed = []
	at org.codehaus.groovy.runtime.InvokerHelper.createAssertError(InvokerHelper.java:416)
	at com.datadog.appsec.php.integration.TelemetryExtendedHeartbeatTests.extended heartbeat re-emits configuration, dependencies and integrations(TelemetryExtendedHeartbeatTests.groovy:70)
	at java.base/java.lang.reflect.Method.invoke(Method.java:569)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)

Not introduced in this PR.

DataDog/apm-reliability/dd-trace-php | ASAN test_c: [8.5, arm64]     

DataDog/apm-reliability/dd-trace-php | PHP language tests: [7.2, amd64, zts]     

View all 22 failed jobs.

ℹ️ Info

No other issues found (see more)

❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 0.00%
• Overall Coverage: 54.04% (-0.04%)

Useful? React with 👍 / 👎

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 877680d | Docs | Datadog PR Page | Give us feedback!}

[pr-commenter]

Benchmarks [ profiler ]

Benchmark execution time: 2026-06-23 16:57:16

Comparing candidate commit 877680d in PR branch levi/otel-thread-context with baseline commit 8499f59 in branch master.

Found 2 performance improvements and 3 performance regressions! Performance is the same for 23 metrics, 8 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:php-profiler-timeline-memory-control

• 🟥 cpu_user_time [+31.470ms; +41.555ms] or [+5.249%; +6.931%]
• 🟥 execution_time [+34.393ms; +39.120ms] or [+5.488%; +6.243%]

scenario:php-profiler-timeline-memory-with-profiler

• 🟥 execution_time [+24.672ms; +40.985ms] or [+2.349%; +3.902%]

scenario:walk_stack/50

• 🟩 wall_time [-539.418ns; -529.903ns] or [-3.374%; -3.315%]

scenario:walk_stack/99

• 🟩 wall_time [-601.193ns; -596.759ns] or [-3.760%; -3.733%]

[pr-commenter]

Benchmarks [ tracer ]

Benchmark execution time: 2026-06-15 22:05:54

Comparing candidate commit a449010 in PR branch levi/otel-thread-context with baseline commit 1d6b7ca in branch master.

Found 1 performance improvements and 3 performance regressions! Performance is the same for 190 metrics, 0 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:MessagePackSerializationBench/benchMessagePackSerialization-opcache

• 🟩 execution_time [-4.916µs; -2.944µs] or [-4.333%; -2.595%]

scenario:PDOBench/benchPDOOverhead

• 🟥 execution_time [+9.550µs; +11.833µs] or [+3.750%; +4.647%]

scenario:PDOBench/benchPDOOverheadWithDBM

• 🟥 execution_time [+9.456µs; +12.357µs] or [+3.703%; +4.839%]

scenario:PHPRedisBench/benchRedisOverhead

• 🟥 execution_time [+53.107µs; +70.110µs] or [+5.279%; +6.969%]

[pr-commenter]

Benchmarks [ appsec ]

Benchmark execution time: 2026-06-23 17:24:07

Comparing candidate commit 877680d in PR branch levi/otel-thread-context with baseline commit 8499f59 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 12 metrics, 0 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 ----------------------------------'