sdk/trace: add trace.WithAllowKeyDuplication by Dipanshusinghh · Pull Request #8488 · open-telemetry/opentelemetry-go

Dipanshusinghh · 2026-06-19T04:47:57Z

Adds WithAllowKeyDuplication() to sdk/trace as a TracerProviderOption to opt out of the attribute map key deduplication introduced in #8471.

Instead of checking a boolean flag on every span operation (the approach reverted in 5fa1035), this swaps a function pointer once at TracerProvider construction — keeping the hot path completely branch-free with no per-operation overhead.

⚠️ Warning: Enabling this option allows spans to contain semantically ambiguous duplicate attribute keys. Downstream exporters and collectors may handle these differently. Use only if you have explicitly verified your pipeline supports duplicate keys.

Benchmarks

goos: windows
goarch: amd64
pkg: go.opentelemetry.io/otel/sdk/trace
cpu: AMD Ryzen 5 5500U with Radeon Graphics

1. Baseline Comparison (vs `main`)

benchstat comparing base commit 7128e65 to this branch — verifying no regression in the default (deduplication enabled) path.

Rows marked ~ indicate no statistically significant change (p > 0.05).
The +7.26% on SpanWithAttributes_4 appears to be noise at n=5 and does not reproduce consistently; happy to rerun at n=20 if needed.

│ sec/op vs base │ StartEndSpan/AlwaysSample-12 1018.0n ~ (p=0.841 n=5) StartEndSpan/NeverSample-12 542.9n ~ (p=0.548 n=5) SpanWithAttributes_4/AlwaysSample-12 1.876µ +7.26% (p=0.008 n=5) SpanWithAttributes_4/NeverSample-12 842.9n ~ (p=0.310 n=5) SpanWithEvents_4/AlwaysSample-12 2.154µ ~ (p=0.079 n=5) SpanWithEvents_4/NeverSample-12 571.5n ~ (p=0.310 n=5) geomean 1.608µ +5.45%

B/op and allocs/op: no change across all benchmarks.

The +5.45% geomean is driven entirely by the one marginal SpanWithAttributes_4 result; all other benchmarks are within noise.

2. WithAllowKeyDuplication Speedup

Benchmarks comparing deduplication enabled vs. disabled, with and without duplicate keys.

Operation	Deduplication	Keys	ns/op	B/op	allocs/op
SetAttributes	Enabled	With Duplicates	2656	1168	5
SetAttributes	Disabled	With Duplicates	2391	976	3
SetAttributes	Enabled	Without Duplicates	2152	848	3
SetAttributes	Disabled	Without Duplicates	2106	848	3
AddEvent	Enabled	With Duplicates	3690	1736	9
AddEvent	Disabled	With Duplicates	2388	1096	6
AddEvent	Enabled	Without Duplicates	2724	968	6
AddEvent	Disabled	Without Duplicates	1838	968	6

With duplicate keys (opt-in benefit):
ns/op: −10% (SetAttributes), −35% (AddEvent)
B/op: −16% (SetAttributes), −37% (AddEvent)
allocs/op: −40% (SetAttributes), −33% (AddEvent)

Without duplicate keys (default path):
No change — fast path is completely unaffected.

Add TestSpanAttributeCapacity_WithAllowKeyDuplication to cover the addOverCapAttrsNoDup code path that is exercised when WithAllowKeyDuplication is enabled and attributes exceed AttributeCountLimit. Test cases cover: under/at/over capacity, split calls that cross the limit, invalid attributes, and a mix of valid-at-capacity followed by invalid attrs.

pellared · 2026-06-19T05:04:58Z

Please revert the changes related to code generation (which is not related to the issue this PR is trying to solve).
Please provide benchstat results in the PR description.

codecov · 2026-06-19T05:23:56Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.1%. Comparing base (e35d473) to head (d9b6d66).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff           @@
##            main   #8488    +/-   ##
======================================
  Coverage   84.0%   84.1%            
======================================
  Files        329     331     +2     
  Lines      26068   26506   +438     
======================================
+ Hits       21919   22312   +393     
- Misses      3768    3788    +20     
- Partials     381     406    +25

Files with missing lines	Coverage Δ
sdk/trace/provider.go	`94.5% <100.0%> (+0.7%)`	⬆️
sdk/trace/span.go	`84.2% <100.0%> (+0.2%)`	⬆️

... and 11 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

pellared · 2026-06-19T06:26:14Z

Marking as draft. Please make it "ready for review" once feedback is addressed. Please also avoid using force-push as described in CONTRIBUTING.md.

…rks matrix

pellared

I made a quick review.
Can you compare benchmarks results with main using benchstat for the go.opentelemetry.io/otel/sdk/trace package and add the results in the PR description?

Dipanshusinghh · 2026-06-19T09:47:07Z

I made a quick review. Can you compare benchmarks results with main using benchstat for the go.opentelemetry.io/otel/sdk/trace package and add the results in the PR description?

Done! Added benchstat results comparing base (7128e65) to this branch in the PR description — no regression on the default path, and WithAllowKeyDuplication speedups are shown as a table.

…n style

…ttributes

pellared · 2026-06-19T10:25:40Z

Please update the PR description after the changes.

Dipanshusinghh · 2026-06-19T10:30:35Z

Please update the PR description after the changes.

Done i have updated the PR discription.

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MrAlias · 2026-08-11T15:15:15Z

@Dipanshusinghh please merge main, resolve all threads that you have addressed, restore the accidentially removed changelog entry, fix the stale comments.

Dipanshusinghh · 2026-08-11T15:23:39Z

@Dipanshusinghh please merge main, resolve all threads that you have addressed, restore the accidentially removed changelog entry, fix the stale comments.

will do this by today
thnx !

…uplication # Conflicts: # CHANGELOG.md # sdk/trace/provider.go # sdk/trace/span.go

Dipanshusinghh · 2026-08-11T19:44:55Z

@MrAlias PTAL !

MrAlias · 2026-08-12T14:33:34Z

resolve all threads that you have addressed

@Dipanshusinghh are the unresolved threads still works in progress? Do you have permissions to resolve the threads?

Dipanshusinghh · 2026-08-12T16:53:49Z

resolve all threads that you have addressed

@Dipanshusinghh are the unresolved threads still works in progress? Do you have permissions to resolve the threads?

sorry just forgot to click the resolve button! done now thnx

Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

Dipanshusinghh requested review from MrAlias, XSAM, dashpole, dmathieu, flc1125 and pellared as code owners June 19, 2026 04:47

Dipanshusinghh added 2 commits June 19, 2026 10:19

feat: add trace.WithAllowKeyDuplication (open-telemetry#8480)

699c4c3

Dipanshusinghh changed the title ~~feat(trace): add WithAllowKeyDuplication option~~ sdk/trace: add trace.WithAllowKeyDuplication Jun 19, 2026

Dipanshusinghh force-pushed the feature/allow-key-duplication branch from 03674ce to 2084182 Compare June 19, 2026 05:21

pellared reviewed Jun 19, 2026

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Comment thread sdk/trace/benchmark_test.go

pellared marked this pull request as draft June 19, 2026 06:26

Dipanshusinghh added 2 commits June 19, 2026 13:09

sdk/trace: refactor allow key duplication benchmarks into sub-benchma…

9b34734

…rks matrix

sdk/trace: fix gofumpt formatting and usetesting warnings in benchmarks

686e418

Dipanshusinghh marked this pull request as ready for review June 19, 2026 08:36

Dipanshusinghh requested a review from pellared June 19, 2026 08:36

pellared reviewed Jun 19, 2026

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sdk/trace: revert unrelated nil checks and guard dedupeSpanAttrs

5788929

Dipanshusinghh requested a review from pellared June 19, 2026 09:44

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Dipanshusinghh added 3 commits June 19, 2026 15:24

sdk/trace: refactor allow key duplication benchmarks into table-drive…

9aae4ad

…n style

sdk/trace: simplify benchmarks using slice subsets for deduplicated a…

87a0fe8

…ttributes

sdk/trace: fix formatting and usetesting warnings in benchmarks

e5a1db2

Dipanshusinghh requested a review from pellared June 19, 2026 10:21

Dipanshusinghh force-pushed the feature/allow-key-duplication branch from 8ec3b0b to 75ba388 Compare June 27, 2026 03:19

sdk/trace: fix trailing blank lines in CHANGELOG

e7c44d8

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Comment thread sdk/trace/trace_test.go Outdated

sdk/trace: fix Copilot review suggestions

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Dipanshusinghh requested a review from dashpole July 9, 2026 14:06

Merge upstream/main into feature/allow-key-duplication

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Comment thread sdk/trace/span.go Outdated

docs(trace): update comment to reflect WithAllowKeyDuplication opt-out

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Mujib-Ahasan mentioned this pull request Aug 2, 2026

Add metric.WithAllowKeyDuplication #8479

Open

MrAlias added this to the v1.46.0 milestone Aug 6, 2026

MrAlias mentioned this pull request Aug 11, 2026

sdk/metric: add metric.WithAllowKeyDuplication #8709

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Dipanshusinghh and others added 3 commits August 12, 2026 00:16

Merge remote-tracking branch 'upstream/main' into feature/allow-key-d…

17e3623

…uplication # Conflicts: # CHANGELOG.md # sdk/trace/provider.go # sdk/trace/span.go

fix: move CHANGELOG entries to Unreleased section

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Merge branch 'main' into feature/allow-key-duplication

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MrAlias reviewed Aug 13, 2026

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Comment thread CHANGELOG.md Outdated

Update CHANGELOG.md

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Co-authored-by: Tyler Yahn <MrAlias@users.noreply.github.com>

Dipanshusinghh requested a review from MrAlias August 13, 2026 17:57

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Benchmarks

1. Baseline Comparison (vs main)

2. WithAllowKeyDuplication Speedup

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Dipanshusinghh commented Jun 19, 2026 •

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1. Baseline Comparison (vs `main`)

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