chore: release v39.0.0

[hoolioh]

What does this PR do?

Release v39

[datadog-prod-us1-5]

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 75.30% (+0.15%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 2797872 | Docs | Datadog PR Page | Give us feedback!}

[dd-octo-sts]

Artifact Size Benchmark Report

aarch64-alpine-linux-musl

Artifact	Baseline	Commit	Change
/aarch64-alpine-linux-musl/lib/libdatadog_profiling.so	8.14 MB	8.14 MB	0% (0 B) 👌
/aarch64-alpine-linux-musl/lib/libdatadog_profiling.a	88.19 MB	88.19 MB	-0% (-2.00 KB) 👌

aarch64-unknown-linux-gnu

Artifact	Baseline	Commit	Change
/aarch64-unknown-linux-gnu/lib/libdatadog_profiling.a	99.33 MB	99.33 MB	-0% (-192 B) 👌
/aarch64-unknown-linux-gnu/lib/libdatadog_profiling.so	10.96 MB	10.96 MB	+0% (+32 B) 👌

libdatadog-x64-windows

Artifact	Baseline	Commit	Change
/libdatadog-x64-windows/debug/dynamic/datadog_profiling_ffi.dll	26.32 MB	26.32 MB	+0% (+512 B) 👌
/libdatadog-x64-windows/debug/dynamic/datadog_profiling_ffi.lib	93.42 KB	93.42 KB	0% (0 B) 👌
/libdatadog-x64-windows/debug/dynamic/datadog_profiling_ffi.pdb	189.36 MB	189.33 MB	--.01% (-32.00 KB) 💪
/libdatadog-x64-windows/debug/static/datadog_profiling_ffi.lib	986.64 MB	987.01 MB	+.03% (+374.44 KB) 🔍
/libdatadog-x64-windows/release/dynamic/datadog_profiling_ffi.dll	8.61 MB	8.61 MB	0% (0 B) 👌
/libdatadog-x64-windows/release/dynamic/datadog_profiling_ffi.lib	93.42 KB	93.42 KB	0% (0 B) 👌
/libdatadog-x64-windows/release/dynamic/datadog_profiling_ffi.pdb	25.31 MB	25.31 MB	0% (0 B) 👌
/libdatadog-x64-windows/release/static/datadog_profiling_ffi.lib	50.42 MB	50.42 MB	+0% (+914 B) 👌

libdatadog-x86-windows

Artifact	Baseline	Commit	Change
/libdatadog-x86-windows/debug/dynamic/datadog_profiling_ffi.dll	22.94 MB	22.94 MB	-0% (-512 B) 👌
/libdatadog-x86-windows/debug/dynamic/datadog_profiling_ffi.lib	94.89 KB	94.89 KB	0% (0 B) 👌
/libdatadog-x86-windows/debug/dynamic/datadog_profiling_ffi.pdb	194.18 MB	194.18 MB	0% (0 B) 👌
/libdatadog-x86-windows/debug/static/datadog_profiling_ffi.lib	976.07 MB	976.23 MB	+.01% (+169.97 KB) 🔍
/libdatadog-x86-windows/release/dynamic/datadog_profiling_ffi.dll	6.65 MB	6.65 MB	0% (0 B) 👌
/libdatadog-x86-windows/release/dynamic/datadog_profiling_ffi.lib	94.89 KB	94.89 KB	0% (0 B) 👌
/libdatadog-x86-windows/release/dynamic/datadog_profiling_ffi.pdb	27.22 MB	27.22 MB	0% (0 B) 👌
/libdatadog-x86-windows/release/static/datadog_profiling_ffi.lib	48.01 MB	48.01 MB	-0% (-900 B) 👌

x86_64-alpine-linux-musl

Artifact	Baseline	Commit	Change
/x86_64-alpine-linux-musl/lib/libdatadog_profiling.a	78.55 MB	78.55 MB	-0% (-1.32 KB) 👌
/x86_64-alpine-linux-musl/lib/libdatadog_profiling.so	9.04 MB	9.04 MB	0% (0 B) 👌

x86_64-unknown-linux-gnu

Artifact	Baseline	Commit	Change
/x86_64-unknown-linux-gnu/lib/libdatadog_profiling.a	94.18 MB	94.18 MB	+0% (+2.96 KB) 👌
/x86_64-unknown-linux-gnu/lib/libdatadog_profiling.so	11.02 MB	11.02 MB	0% (0 B) 👌

[pr-commenter]

Benchmarks

Comparison

Benchmark execution time: 2026-08-06 08:53:28

Comparing candidate commit 2797872 in PR branch julio/release-v39 with baseline commit 9ac89b9 in branch main.

Found 0 performance improvements and 1 performance regressions! Performance is the same for 139 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:profiles_dictionary/profile_string_inserts/threads/1

• 🟥 execution_time [+15.281µs; +17.431µs] or [+4.018%; +4.584%]

Benchmark execution time: 2026-08-06 09:03:10

Comparing candidate commit 2797872 in PR branch julio/release-v39 with baseline commit 9ac89b9 in branch main.

Found 2 performance improvements and 7 performance regressions! Performance is the same for 159 metrics, 10 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:datadog_sample_span/name_pattern_rule_not_matching/wall_time

• 🟩 execution_time [-8.741ns; -8.644ns] or [-5.238%; -5.180%]

scenario:glob_matcher/unicode_exact_match/wall_time

• 🟥 execution_time [+4.034ns; +4.101ns] or [+5.477%; +5.567%]

scenario:no_profiler/short_circuit/4096

• 🟥 execution_time [+22.827ns; +23.034ns] or [+24.252%; +24.472%]

scenario:profiler_attached/fast_path_system/4096

• 🟩 execution_time [-14.203ns; -14.052ns] or [-13.516%; -13.372%]

scenario:profiler_attached/slow_path_system/4096

• 🟥 execution_time [+8.730ns; +8.877ns] or [+6.027%; +6.128%]

scenario:trace_buffer/2_senders/no_delay

• 🟥 execution_time [+90.295µs; +105.383µs] or [+5.370%; +6.267%]
• 🟥 throughput [-63328.230op/s; -54277.398op/s] or [-5.913%; -5.068%]

scenario:trace_buffer/4_senders/no_delay

• 🟥 execution_time [+246.562µs; +260.226µs] or [+6.898%; +7.280%]
• 🟥 throughput [-68378.364op/s; -64925.281op/s] or [-6.789%; -6.446%]

Candidate

Omitted due to size.

Baseline

Omitted due to size.