[PROF-12846] Fix profiler not categorizing its own sleep/waiting in timeline

[ivoanjo]

What does this PR do?

This PR extends the timeline thread state categorization code to recognize two frames from the profiler.

Motivation:

These two frames quite commonly show up on application profiles, and so its useful for them to be correctly categorized.

Change log entry

Yes. Fix profiler not categorizing its own sleep/waiting in timeline

Additional Notes:

Getting a thread inside the _native_sampling_loop for testing in this case is quite awkward so I only added test coverage for the _native_idle_sampling_loop which is quite easy to trigger.

How to test the change?

This tiny test script produced samples from both of these frames that were uncategorized:

DD_PROFILING_ENABLED=true DD_SERVICE=ivoanjo-testing-categ-fix bundle exec ddprofrb exec ruby -e "end_at = Time.now + 3; while Time.now < end_at; end"

Here's how it looked before:

and how it looks now:

[datadog-datadog-prod-us1]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage
• Patch Coverage: 100.00%
• Total Coverage: 98.45% (+0.01%)

View detailed report

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 883c378 | Docs | Was this helpful? Give us feedback!}

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-10-24 10:35:41

Comparing candidate commit 883c378 in PR branch ivoanjo/prof-12846-incorrect-state-category with baseline commit 7e292a6 in branch master.

Found 1 performance improvements and 0 performance regressions! Performance is the same for 43 metrics, 2 unstable metrics.

scenario:profiling - Allocations ()

• 🟩 throughput [+371394.072op/s; +394651.168op/s] or [+12.795%; +13.596%]