[PROF-14464] Record the total time spent waiting for the GVL as a metric by eregon · Pull Request #5569 · DataDog/dd-trace-rb

eregon · 2026-04-09T13:20:42Z

What does this PR do?

Record the total time spent waiting for the GVL as a metric.
See #3433.

Motivation:

That issue.

Change log entry

Yes. Added metric for total time spent waiting for the GVL.

Additional Notes:

Yes, I'm experimenting with Cursor.

How to test the change?

github-actions · 2026-04-09T13:20:54Z

Thank you for updating Change log entry section 👏

^{Visited at: 2026-04-09 14:13:34 UTC}

datadog-datadog-prod-us1 · 2026-04-09T13:38:45Z

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 97.21% (-0.01%)

_{This comment will be updated automatically if new data arrives.

🔗 Commit SHA: 2556ab2 | Docs | Datadog PR Page | Give us feedback!}

pr-commenter · 2026-04-09T14:16:52Z

Benchmarks

Benchmark execution time: 2026-05-04 09:50:38

Comparing candidate commit 2556ab2 in PR branch bd/gvl-metrics with baseline commit bb919c7 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 45 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 ----------------------------------'

ivoanjo

Looks good!

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ivoanjo

👍 LGTM.

From the Ruby side we're in great shape, yet we'll probably want to do one last "test this end-to-end" before merging, just in case we missed some small detail that makes the backend unhappy.

eregon · 2026-05-04T09:57:40Z

CI was green before rebase, the CI failures are unrelated to this PR and caused by #5656, merging.

…o used as a metric * See #5569

github-actions Bot added the profiling Involves Datadog profiling label Apr 9, 2026

eregon force-pushed the bd/gvl-metrics branch 2 times, most recently from 5aee7cb to 472c7ee Compare April 9, 2026 13:51

ivoanjo reviewed Apr 9, 2026

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Comment thread ext/datadog_profiling_native_extension/collectors_cpu_and_wall_time_worker.c Outdated

eregon force-pushed the bd/gvl-metrics branch 3 times, most recently from cc1ffe9 to ca5bd7a Compare April 9, 2026 16:41

ivoanjo reviewed Apr 9, 2026

View reviewed changes

Comment thread lib/datadog/profiling/exporter.rb Outdated

Comment thread spec/datadog/profiling/flush_spec.rb Outdated

eregon commented Apr 14, 2026

View reviewed changes

Comment thread lib/datadog/profiling/flush.rb

eregon mentioned this pull request Apr 28, 2026

Add a metric for total wait time on GVL #5651

Closed

eregon force-pushed the bd/gvl-metrics branch 3 times, most recently from 767eaab to 3c1bb09 Compare April 29, 2026 10:26

eregon marked this pull request as ready for review April 29, 2026 10:27

eregon requested review from a team as code owners April 29, 2026 10:27

chatgpt-codex-connector Bot reviewed Apr 29, 2026

View reviewed changes

Comment thread ext/datadog_profiling_native_extension/collectors_cpu_and_wall_time_worker.c Outdated

eregon force-pushed the bd/gvl-metrics branch 2 times, most recently from e1d7d9a to 49a8c91 Compare April 29, 2026 12:24

ivoanjo approved these changes Apr 29, 2026

View reviewed changes

Comment thread lib/datadog/profiling/flush.rb

eregon force-pushed the bd/gvl-metrics branch from 49a8c91 to 062ef17 Compare April 30, 2026 09:58

Record the total time spent waiting for the GVL as a metric

2556ab2

eregon force-pushed the bd/gvl-metrics branch from 062ef17 to 2556ab2 Compare May 4, 2026 09:24

eregon merged commit b02fa7b into master May 4, 2026
435 of 439 checks passed

eregon deleted the bd/gvl-metrics branch May 4, 2026 09:58

dd-octo-sts Bot added this to the 2.32.0 milestone May 4, 2026

eregon changed the title ~~Record the total time spent waiting for the GVL as a metric~~ [PROF-14464] Record the total time spent waiting for the GVL as a metric May 4, 2026

eregon mentioned this pull request May 5, 2026

Add metrics around GVL #3433

Closed

eregon linked an issue May 5, 2026 that may be closed by this pull request

Add metrics around GVL #3433

Closed

marcotc mentioned this pull request May 7, 2026

Bump to version 2.32.0 #5710

Merged

eregon mentioned this pull request May 13, 2026

Deprecate the timeline_enabled option which is redundant with gvl_enabled #5750

Merged

eregon added a commit that referenced this pull request May 21, 2026

Enable GVL profiling even if timeline is disabled since it is now als…

2da61c0

…o used as a metric * See #5569

eregon added a commit that referenced this pull request May 21, 2026

Enable GVL profiling even if timeline is disabled since it is now als…

19c21c5

…o used as a metric * See #5569

eregon added a commit that referenced this pull request May 26, 2026

Enable GVL profiling even if timeline is disabled since it is now als…

cb58654

…o used as a metric * See #5569

eregon added a commit that referenced this pull request May 26, 2026

Enable GVL profiling even if timeline is disabled since it is now als…

df2a6a5

…o used as a metric * See #5569

eregon added a commit that referenced this pull request May 26, 2026

Enable GVL profiling even if timeline is disabled since it is now als…

13c29ce

…o used as a metric * See #5569

eregon added a commit that referenced this pull request May 27, 2026

Enable GVL profiling even if timeline is disabled since it is now als…

2656a63

…o used as a metric * See #5569

eregon added a commit that referenced this pull request May 27, 2026

Enable GVL profiling even if timeline is disabled since it is now als…

53de3a4

…o used as a metric * See #5569

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[PROF-14464] Record the total time spent waiting for the GVL as a metric#5569

[PROF-14464] Record the total time spent waiting for the GVL as a metric#5569
eregon merged 1 commit into
masterfrom
bd/gvl-metrics

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