chore: improvements to ETP by hannahkm · Pull Request #4586 · DataDog/dd-trace-go

hannahkm · 2026-03-23T19:18:53Z

What does this PR do?

Set dummy values for when serialization fails to prevent failures during decoding
Removes duplicated serialization for span links
Adds warning logs for failed serialization (inlined to prevent increased allocations)
Updates string table to use string keys instead of stringValue in the indices map to reduce map lookup times
Further reduces lookups by getting common values during preexisting map iteration

Motivation

Align with RFC and Java implementation. Improvements to performance.

Reviewer's Checklist

Changed code has unit tests for its functionality at or near 100% coverage.
System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
There is a benchmark for any new code, or changes to existing code.
If this interacts with the agent in a new way, a system test has been added.
New code is free of linting errors. You can check this by running make lint locally.
New code doesn't break existing tests. You can check this by running make test locally.
Add an appropriate team label so this PR gets put in the right place for the release notes.
All generated files are up to date. You can check this by running make generate locally.
Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild. Make sure all nested modules are up to date by running make fix-modules locally.

Unsure? Have a question? Request a review!

codecov · 2026-03-23T19:23:01Z

Codecov Report

❌ Patch coverage is 64.70588% with 24 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.75%. Comparing base (43ac765) to head (e4cd6de).

Files with missing lines	Patch %	Lines
ddtrace/tracer/payload_v1.go	64.70%	19 Missing and 5 partials ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
ddtrace/tracer/payload_v1.go	`68.58% <64.70%> (ø)`

... and 439 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

datadog-datadog-prod-us1 · 2026-03-23T19:23:07Z

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 64.18%
• Overall Coverage: 60.09%

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

🔗 Commit SHA: e4cd6de | Docs | Datadog PR Page | Was this helpful? React with 👍/👎 or give us feedback!}

pr-commenter · 2026-03-23T19:40:52Z

Benchmarks

Benchmark execution time: 2026-04-14 09:00:07

Comparing candidate commit e4cd6de in PR branch hannahkm/v1-followups with baseline commit 43ac765 in branch main.

Found 15 performance improvements and 0 performance regressions! Performance is the same for 203 metrics, 6 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:BenchmarkPayloadVersions/detailed_1000spans/v1_0-25

🟩 allocated_mem [-7 bytes; -7 bytes] or [-6.422%; -6.422%]
🟩 execution_time [-54.997µs; -53.677µs] or [-9.246%; -9.024%]

scenario:BenchmarkPayloadVersions/detailed_100spans/v1_0-25

🟩 allocated_mem [-1 bytes; -1 bytes] or [-3.030%; -3.030%]
🟩 execution_time [-6.020µs; -5.591µs] or [-9.863%; -9.161%]

scenario:BenchmarkPayloadVersions/detailed_10spans/v1_0-25

🟩 execution_time [-728.679ns; -692.121ns] or [-9.897%; -9.400%]

scenario:BenchmarkPayloadVersions/detailed_1spans/v1_0-25

🟩 execution_time [-83.402ns; -74.398ns] or [-5.503%; -4.909%]

scenario:BenchmarkPayloadVersions/metastruct_1000spans/v1_0-25

🟩 execution_time [-55.679µs; -53.993µs] or [-16.710%; -16.204%]

scenario:BenchmarkPayloadVersions/metastruct_100spans/v1_0-25

🟩 execution_time [-5.602µs; -5.443µs] or [-14.708%; -14.290%]

scenario:BenchmarkPayloadVersions/metastruct_10spans/v1_0-25

🟩 execution_time [-717.407ns; -666.793ns] or [-10.325%; -9.597%]

scenario:BenchmarkPayloadVersions/metastruct_1spans/v1_0-25

🟩 execution_time [-133.741ns; -86.259ns] or [-3.522%; -2.272%]

scenario:BenchmarkPayloadVersions/simple_1000spans/v1_0-25

🟩 allocated_mem [-6 bytes; -6 bytes] or [-11.321%; -11.321%]
🟩 execution_time [-55.054µs; -54.246µs] or [-19.200%; -18.919%]

scenario:BenchmarkPayloadVersions/simple_100spans/v1_0-25

🟩 execution_time [-5.773µs; -5.539µs] or [-19.360%; -18.575%]

scenario:BenchmarkPayloadVersions/simple_10spans/v1_0-25

🟩 execution_time [-708.636ns; -683.364ns] or [-17.866%; -17.229%]

scenario:BenchmarkPayloadVersions/simple_1spans/v1_0-25

🟩 execution_time [-132.981ns; -119.879ns] or [-11.829%; -10.663%]

darccio · 2026-03-26T08:22:02Z

@codex review

chatgpt-codex-connector · 2026-03-26T08:26:46Z

Codex Review: Didn't find any major issues. Nice work!

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darccio

In general it's fine, but the regressions must be addressed.

I'm curious why we need to set _dd.span_links when we could just postpone the serialization until the very moment we really need to.

…an links

This reverts commit aa8ebfa.

kakkoyun

LGTM! Tedious work.

darccio · 2026-04-13T13:59:56Z

@codex review

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: c65531fd5d

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hannahkm · 2026-04-13T16:44:29Z

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

🤖 Generated with Claude Code

_{- If this code review was useful, please react with 👍. Otherwise, react with 👎.}

darccio

LGTM with just a smol nit.

darccio · 2026-04-13T16:49:31Z

+//go:noinline
+func warnUnsupportedValue(t uint32) {
+	log.Warn("failed to serialize unsupported type: %d", t)
+}


Why does it need the go:inline directive?

:hmmnod: It's not strictly necessary here, I think, since the callers are already pretty complex, so there's no chance of inlining unless we simplify the them. But that might be difficult...

ddtrace/tracer/payload_v1.go:941:6: cannot inline anyValue.encode: function too complex: cost 1059 exceeds budget 80

ddtrace/tracer/payload_v1.go:713:6: cannot inline (*payloadV1).encodeSpanEvents: function too complex: cost 1517 exceeds budget 80

So, tl;dr, probably doesn't need go:noinline

hannahkm added 3 commits March 23, 2026 09:21

wip: default value for failed serialization

db1fbc2

write dummy value as a byte for meta_struct

44211b7

dont double encode span links on spans

f3ac9a2

hannahkm added 4 commits March 24, 2026 10:24

fix: reduce heap allocs?

fef304e

trigger tests

5a8e764

lint: don't use %v

f81c6ec

fix: array length with _dd.span_links was wrong

ec8baf2

hannahkm marked this pull request as ready for review March 25, 2026 21:32

hannahkm requested a review from a team as a code owner March 25, 2026 21:32

Merge branch 'main' into hannahkm/v1-followups

7cf57c5

darccio requested changes Mar 26, 2026

View reviewed changes

Comment thread ddtrace/tracer/payload_v1.go Outdated

Comment thread ddtrace/tracer/payload_v1.go Outdated

hannahkm added 6 commits March 30, 2026 10:43

inlining fixes

682035b

attempt: write array header after contents to save time on reading sp…

6613e9f

…an links

get meta values proactively

0a7fffe

only create string table if it doesn't already exist

91cecd6

trigger pipelines

a4393ae

delete outdated static checks workflow

aa8ebfa

hannahkm requested a review from a team as a code owner April 1, 2026 18:07

hannahkm and others added 4 commits April 1, 2026 14:08

Revert "delete outdated static checks workflow"

30e36d2

This reverts commit aa8ebfa.

Merge branch 'main' into hannahkm/v1-followups

6098c60

use built in string type for indices map

1f272f8

Merge branch 'main' into hannahkm/v1-followups

089e444

kakkoyun approved these changes Apr 8, 2026

View reviewed changes

hannahkm added 2 commits April 8, 2026 13:25

Merge branch 'main' into hannahkm/v1-followups

eb52b87

Merge branch 'main' into hannahkm/v1-followups

b2465d5

gh-worker-dd-devflow-36fce6 Bot added mergequeue-status: waiting mergequeue-status: removed and removed mergequeue-status: waiting mergequeue-status: removed labels Apr 8, 2026

Merge branch 'main' into hannahkm/v1-followups

c65531f

kakkoyun requested review from darccio and removed request for darccio April 9, 2026 09:51

chatgpt-codex-connector Bot reviewed Apr 13, 2026

View reviewed changes

Comment thread ddtrace/tracer/payload_v1.go

reset string table on encode

64548fb

fix: use warnUnsupportedValue func instead of log.Warn

de0fcfc

darccio reviewed Apr 13, 2026

View reviewed changes

wip: more benchmarking for payloads

18d426e

darccio approved these changes Apr 14, 2026

View reviewed changes

Merge branch 'main' into hannahkm/v1-followups

e4cd6de

gh-worker-dd-devflow-36fce6 Bot added mergequeue-status: queued mergequeue-status: in_progress and removed mergequeue-status: removed mergequeue-status: queued labels Apr 14, 2026

gh-worker-dd-mergequeue-cf854d Bot merged commit 10a3be6 into main Apr 14, 2026
215 checks passed

gh-worker-dd-mergequeue-cf854d Bot deleted the hannahkm/v1-followups branch April 14, 2026 09:19

gh-worker-dd-devflow-36fce6 Bot added mergequeue-status: done and removed mergequeue-status: in_progress labels Apr 14, 2026

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What does this PR do?

Motivation

Reviewer's Checklist

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Benchmarks

Explanation

More details about the CI and significant changes

scenario:BenchmarkPayloadVersions/detailed_1000spans/v1_0-25

scenario:BenchmarkPayloadVersions/detailed_100spans/v1_0-25

scenario:BenchmarkPayloadVersions/detailed_10spans/v1_0-25

scenario:BenchmarkPayloadVersions/detailed_1spans/v1_0-25

scenario:BenchmarkPayloadVersions/metastruct_1000spans/v1_0-25

scenario:BenchmarkPayloadVersions/metastruct_100spans/v1_0-25

scenario:BenchmarkPayloadVersions/metastruct_10spans/v1_0-25

scenario:BenchmarkPayloadVersions/metastruct_1spans/v1_0-25

scenario:BenchmarkPayloadVersions/simple_1000spans/v1_0-25

scenario:BenchmarkPayloadVersions/simple_100spans/v1_0-25

scenario:BenchmarkPayloadVersions/simple_10spans/v1_0-25

scenario:BenchmarkPayloadVersions/simple_1spans/v1_0-25

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hannahkm commented Apr 13, 2026

Code review

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hannahkm commented Mar 23, 2026 •

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