Fix raise_error() and grab_gvl_and_raise() to use rb_vsprintf() so PRIsVALUE works by eregon · Pull Request #5857 · DataDog/dd-trace-rb

eregon · 2026-06-03T14:57:09Z

So raise_error(rb_eRuntimeError, "foo %"PRIsVALUE" bar", some_ruby_object) calls #to_s and doesn't print an integer.
(or "%+"PRIsVALUE which calls #inspect and not print "+123")
Pass the va_list through rb_thread_call_with_gvl and call rb_vsprintf()
inside the callback where the GVL is held (rb_vsprintf allocates Ruby
objects). This is safe because rb_thread_call_with_gvl is synchronous so
the parent stack frame (where the va_list lives) is still alive.

What does this PR do?
^

Motivation:
Correctness and useful error messages.

Change log entry

Yes. Fix some exception messages which were not formatted correctly.

Additional Notes:

How to test the change?

…e GVL

datadog-official · 2026-06-03T15:00:18Z

Tests

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 97.08% (-0.00%)

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

🔗 Commit SHA: 133e02e | Docs | Datadog PR Page | Give us feedback!}

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ivoanjo

👍 LGTM, great catch

pr-commenter · 2026-06-03T15:49:20Z

Benchmarks

Benchmark execution time: 2026-06-03 19:48:58

Comparing candidate commit 133e02e in PR branch fix-raise_error-helper with baseline commit ef09ce5 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 ----------------------------------'

…IsVALUE works * So `raise_error(rb_eRuntimeError, "foo %"PRIsVALUE" bar", some_ruby_object)` calls #to_s and doesn't print an integer. (or `"%+"PRIsVALUE` which calls #inspect and not print "+123") * Pass the va_list through rb_thread_call_with_gvl and call rb_vsprintf() inside the callback where the GVL is held (rb_vsprintf allocates Ruby objects). This is safe because rb_thread_call_with_gvl is synchronous so the parent stack frame (where the va_list lives) is still alive. Co-Authored-By: Claude Opus 4.6 <[email protected]>

Now that rb_vsprintf() produces Ruby strings directly, there is no fixed-size C buffer limiting the message length. The artificial 255-char cap is no longer needed. Co-Authored-By: Claude Opus 4.6 <[email protected]>

Test raise_error() via _native_raise_error_value_arg and also through the otel_context_enabled production code path in ThreadContext. Co-Authored-By: Claude Opus 4.6 <[email protected]>

Fix private_raise_enforce_syserr() not using telemetry when it has th…

5aa34b1

…e GVL

eregon requested review from a team as code owners June 3, 2026 14:57

dd-octo-sts Bot added the profiling Involves Datadog profiling label Jun 3, 2026

chatgpt-codex-connector Bot reviewed Jun 3, 2026

View reviewed changes

Comment thread ext/datadog_profiling_native_extension/datadog_ruby_common.c

eregon commented Jun 3, 2026

View reviewed changes

Comment thread ext/datadog_profiling_native_extension/ruby_helpers.c Outdated

eregon force-pushed the fix-raise_error-helper branch 2 times, most recently from 6f6e08b to 2ec7ba2 Compare June 3, 2026 15:22

ivoanjo approved these changes Jun 3, 2026

View reviewed changes

Comment thread ext/datadog_profiling_native_extension/ruby_helpers.c Outdated

eregon and others added 3 commits June 3, 2026 21:22

Remove MAX_RAISE_MESSAGE_SIZE truncation for exception messages

006665a

Now that rb_vsprintf() produces Ruby strings directly, there is no fixed-size C buffer limiting the message length. The artificial 255-char cap is no longer needed. Co-Authored-By: Claude Opus 4.6 <[email protected]>

Add spec for a real usage of raise_error() with PRIsVALUE formatting

133e02e

Test raise_error() via _native_raise_error_value_arg and also through the otel_context_enabled production code path in ThreadContext. Co-Authored-By: Claude Opus 4.6 <[email protected]>

eregon force-pushed the fix-raise_error-helper branch from 074e7dc to 133e02e Compare June 3, 2026 19:23

eregon enabled auto-merge June 3, 2026 19:28

eregon merged commit 1c780c6 into master Jun 3, 2026
590 checks passed

eregon deleted the fix-raise_error-helper branch June 3, 2026 19:51

dd-octo-sts Bot added this to the 2.36.0 milestone Jun 3, 2026

This was referenced Jun 4, 2026

Remove unused private_raise_error_formatted() #5860

Merged

Store per_thread_context in each Ruby Thread #5816

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Fix raise_error() and grab_gvl_and_raise() to use rb_vsprintf() so PRIsVALUE works#5857

Fix raise_error() and grab_gvl_and_raise() to use rb_vsprintf() so PRIsVALUE works#5857
eregon merged 4 commits into
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fix-raise_error-helper

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