ci: move PHP language test telemetry to 7.4 and 8.5

[morrisonlevi]

Description

The PHP 7.0 and 7.1 language tests are the only ones with telemetry enabled for cost reasons. However these are also the slowest and regularly time out. PHP 7.1 for instance fails roughly 1/3 of the time and half of those are clearly marked timeouts.

So the hope is to move 7.0/7.1 into the same runtime range as 7.2/7.3 and then slow down 8.4 and 8.5 to pay the telemetry perf tax, since they average 6-7 minutes. We also set DD_SERVICE and DD_VERSION now.

Metric	7.0	7.1	7.2	7.3	7.4	8.5
Parallel runner	No	No	No	No	Yes	Yes
Telemetry in CI	On	On	Off	Off	Off	Off
Min	32m 03s	35m 18s	19m 02s	19m 15s	5m 08s	5m 53s
Median (p50)	37m 05s	40m 59s	22m 03s	22m 03s	5m 33s	6m 38s
Average	38m 10s	41m 34s	22m 28s	22m 24s	6m 02s	6m 59s
p95	46m 13s	46m 13s	25m 22s	24m 52s	8m 37s	9m 09s
Max	47m 52s	48m 01s	29m 38s	29m 28s	10m 53s	10m 46s
Failure rate	12.7%	36.2%	7.1%	7.7%	9.2% (32/346)	5.3% (18/337)

If these jobs start timing out, that's strong evidence that telemetry is at fault. PHP 7.4 and 8.5 language tests have not had any timeouts in the past week.

Preliminary runtimes for 7.4/8.5 is that they roughly double. Locally, I can't reproduce it. It may be that writing logs is slower in CI for some reason, and they have significantly higher log volumes with telemetry enabled. This should be investigated but it's not directly blocking this PR (we had this same problem on PHP 7.0/7.1, I'm just shifting it to 7.4/8.5).

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[datadog-prod-us1-3]

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 68.41% (+0.01%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: cf76264 | Docs | View more details | Give us feedback!}

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-13T16:24:06.129500Z	7de1932	Draft marked ready
🔒 Security Review	✅ Completed 2026-10-13T16:26:38.618187Z	7de1932	Draft marked ready

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[datadog-prod-us1-3]

More details

Generated CI configuration enables telemetry only for PHP 7.4 and 8.5, both using parallel runners, and applies a 40-minute timeout to every language-test job. No actionable defect was identified.

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[pr-commenter]

Benchmarks [ tracer ]

Benchmark execution time: 2026-10-13 16:47:59

Comparing candidate commit 7de1932 in PR branch levi/telemetry-php-lang-tests with baseline commit efd55c0 in branch master.

📊 Benchmarking dashboard

Found 4 performance improvements and 1 performance regressions! Performance is the same for 189 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:ContextPropagationBench/benchInject64Bit-opcache

• 🟥 execution_time [+55.573ns; +148.427ns] or [+2.374%; +6.340%]

scenario:LaravelBench/benchLaravelBaseline

• 🟩 execution_time [-1.658ms; -1.494ms] or [-14.795%; -13.335%]

scenario:PDOBench/benchPDOBaseline

• 🟩 execution_time [-8.370µs; -7.772µs] or [-11.290%; -10.483%]

scenario:PDOBench/benchPDOOverhead

• 🟩 execution_time [-28.744µs; -25.859µs] or [-11.222%; -10.096%]

scenario:PDOBench/benchPDOOverheadWithDBM

• 🟩 execution_time [-47.639µs; -42.796µs] or [-18.631%; -16.737%]