ci(profiling): collect PHP language test core dumps

[realFlowControl]

Description

Enables core dumps for profiler PHP language tests and, when a core is present after a failed job, uploads both the raw core and a GDB report containing all thread backtraces, locals, registers, and shared libraries.

The runner's core_pattern=core and core_uses_pid=0 settings mean this captures at most one core per job.

Why

While working on #4060 one of PHP language tests faild with:

2026-07-25T09:15:44.954690Z 01O ========DIFF========
2026-07-25T09:15:44.954694Z 01O �[1;31m001- array(3) {�[0m
2026-07-25T09:15:44.954795Z 01O �[1;31m002-   [0]=>�[0m
2026-07-25T09:15:44.954802Z 01O �[1;31m003-   int(1)�[0m
2026-07-25T09:15:44.954832Z 01O �[1;31m004-   [1]=>�[0m
2026-07-25T09:15:44.954840Z 01O �[1;31m005-   bool(true)�[0m
2026-07-25T09:15:44.954846Z 01O �[1;31m006-   [2]=>�[0m
2026-07-25T09:15:44.954852Z 01O �[1;31m007-   int(2)�[0m
2026-07-25T09:15:44.954855Z 01O �[1;31m008- }�[0m
2026-07-25T09:15:44.954859Z 01O �[1;32m001+ Segmentation fault�[0m
2026-07-25T09:15:44.954865Z 01O ========DONE========
2026-07-25T09:15:44.954868Z 01O �[1;31mFAIL�[0m Bug #81577: (Exceptions in interrupt handlers: ADD_ARRAY_ELEMENT) [ext/pcntl/tests/bug81577_2.phpt] 

I was not able to reproduce locally, but if it ever happens again, we should have a core dump to poke.

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[datadog-datadog-prod-us1-2]

 

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⚠️ Warnings

🚦 5 Pipeline jobs failed

DataDog/apm-reliability/dd-trace-php | min install tests     

DataDog/apm-reliability/dd-trace-php | test_extension_ci: [7.4]     

DataDog/apm-reliability/dd-trace-php | test_extension_ci: [8.3]     

View all 5 failed jobs.

ℹ️ Info

No other issues found (see more)

🧪 All tests passed
❄️ No new flaky tests detected

🔄 Datadog auto-retried 1 job - 1 passed on retry

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 60.65% (+0.01%)

Useful? React with 👍 / 👎

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[pr-commenter]

Benchmarks [ tracer ]

Benchmark execution time: 2026-07-27 08:25:03

Comparing candidate commit e612a3b in PR branch florian/no-jira-profiler-language-test-core-dumps with baseline commit 39036dc in branch master.

Found 1 performance improvements and 4 performance regressions! Performance is the same for 188 metrics, 1 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

• 🟩 execution_time [-5.516µs; -3.324µs] or [-5.012%; -3.020%]

scenario:SamplingRuleMatchingBench/benchRegexMatching1

• 🟥 execution_time [+60.858ns; +138.342ns] or [+4.109%; +9.340%]

scenario:SamplingRuleMatchingBench/benchRegexMatching2

• 🟥 execution_time [+88.861ns; +171.539ns] or [+6.110%; +11.794%]

scenario:SamplingRuleMatchingBench/benchRegexMatching3

• 🟥 execution_time [+38.038ns; +113.762ns] or [+2.524%; +7.550%]

scenario:SamplingRuleMatchingBench/benchRegexMatching4

• 🟥 execution_time [+83.948ns; +147.852ns] or [+5.794%; +10.204%]