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[Propagators] Improve JaegerPropagator performance#7171

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martincostello merged 3 commits intoopen-telemetry:mainfrom
martincostello:JaegerPropagator-perf
Apr 27, 2026
Merged

[Propagators] Improve JaegerPropagator performance#7171
martincostello merged 3 commits intoopen-telemetry:mainfrom
martincostello:JaegerPropagator-perf

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@martincostello martincostello commented Apr 25, 2026

Changes

Improve the performance of JaegerPropagator for .NET 8+ by using SearchValues<T>.

Benchmark Results

Copilot Summary

JaegerPropagator-perf improves all common Extract benchmarks, while Inject is mixed. Allocations are unchanged across every shared suite.

Suite Method main JaegerPropagator-perf Duration delta Duration ratio Allocation delta Allocation ratio
Sampled=False, UseEncodedDelimiter=False Extract 212.57 ns 98.98 ns -53.4% 0.47x 312 B -> 312 B (0.0%) 1.00x
Sampled=False, UseEncodedDelimiter=False Inject 54.12 ns 28.58 ns -47.2% 0.53x 128 B -> 128 B (0.0%) 1.00x
Sampled=False, UseEncodedDelimiter=True Extract 200.61 ns 92.99 ns -53.6% 0.46x 312 B -> 312 B (0.0%) 1.00x
Sampled=False, UseEncodedDelimiter=True Inject 27.55 ns 28.85 ns +4.7% 1.05x 128 B -> 128 B (0.0%) 1.00x
Sampled=True, UseEncodedDelimiter=False Extract 119.99 ns 89.37 ns -25.5% 0.74x 312 B -> 312 B (0.0%) 1.00x
Sampled=True, UseEncodedDelimiter=False Inject 26.59 ns 28.38 ns +6.7% 1.07x 128 B -> 128 B (0.0%) 1.00x
Sampled=True, UseEncodedDelimiter=True Extract 120.75 ns 89.50 ns -25.9% 0.74x 312 B -> 312 B (0.0%) 1.00x
Sampled=True, UseEncodedDelimiter=True Inject 27.28 ns 27.20 ns -0.3% 1.00x 128 B -> 128 B (0.0%) 1.00x

Overall

  • Extract: faster in every shared suite on JaegerPropagator-perf, with the biggest wins in non-sampled cases (~54% lower duration).
  • Inject: one large win (-47.2%), two small regressions (+4.7% and +6.7%), and one effectively unchanged result.
  • Allocations: no change in any shared benchmark.

Detailed Results

Expand to view

main


BenchmarkDotNet v0.15.8, Windows 11 (10.0.26200.8246/25H2/2025Update/HudsonValley2)
13th Gen Intel Core i7-13700H 2.90GHz, 1 CPU, 20 logical and 14 physical cores
.NET SDK 10.0.203
  [Host]    : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3
  .NET 10.0 : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3

Job=.NET 10.0  Runtime=.NET 10.0  Toolchain=net10.0
Method Sampled UseEncodedDelimiter Mean Error StdDev Ratio RatioSD Gen0 Allocated Alloc Ratio
Extract False False 212.57 ns 4.066 ns 3.804 ns 1.00 0.02 0.0248 312 B 1.00
Inject False False 54.12 ns 2.795 ns 7.975 ns 0.25 0.04 0.0102 128 B 0.41
Extract False True 200.61 ns 3.607 ns 3.542 ns 1.00 0.02 0.0248 312 B 1.00
Inject False True 27.55 ns 0.585 ns 1.220 ns 0.14 0.01 0.0102 128 B 0.41
Extract True False 119.99 ns 2.045 ns 1.708 ns 1.00 0.02 0.0248 312 B 1.00
Inject True False 26.59 ns 0.560 ns 1.144 ns 0.22 0.01 0.0102 128 B 0.41
Extract True True 120.75 ns 2.199 ns 2.057 ns 1.00 0.02 0.0248 312 B 1.00
Inject True True 27.28 ns 0.571 ns 0.984 ns 0.23 0.01 0.0102 128 B 0.41

This PR


BenchmarkDotNet v0.15.8, Windows 11 (10.0.26200.8246/25H2/2025Update/HudsonValley2)
13th Gen Intel Core i7-13700H 2.90GHz, 1 CPU, 20 logical and 14 physical cores
.NET SDK 10.0.203
  [Host]    : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3
  .NET 10.0 : .NET 10.0.7 (10.0.7, 10.0.726.21808), X64 RyuJIT x86-64-v3

Job=.NET 10.0  Runtime=.NET 10.0  Toolchain=net10.0
Method Sampled UseEncodedDelimiter Mean Error StdDev Ratio RatioSD Gen0 Allocated Alloc Ratio
Extract False False 98.98 ns 2.006 ns 2.746 ns 1.00 0.04 0.0248 312 B 1.00
Inject False False 28.58 ns 0.590 ns 1.245 ns 0.29 0.01 0.0102 128 B 0.41
Extract False True 92.99 ns 1.827 ns 2.438 ns 1.00 0.04 0.0248 312 B 1.00
Inject False True 28.85 ns 0.609 ns 1.143 ns 0.31 0.01 0.0102 128 B 0.41
Extract True False 89.37 ns 1.693 ns 1.738 ns 1.00 0.03 0.0248 312 B 1.00
Inject True False 28.38 ns 0.564 ns 1.238 ns 0.32 0.01 0.0102 128 B 0.41
Extract True True 89.50 ns 1.760 ns 1.807 ns 1.00 0.03 0.0248 312 B 1.00
Inject True True 27.20 ns 0.569 ns 1.353 ns 0.30 0.02 0.0102 128 B 0.41

Merge requirement checklist

  • CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
  • Unit tests added/updated
  • Appropriate CHANGELOG.md files updated for non-trivial changes
  • Changes in public API reviewed (if applicable)

@martincostello
[Propagators] Improve JaegerPropagator perf
3a8ede9 
Improve the performance of `JaegerPropagator` for .NET 8+ by using `SearchValues<T>`.
@github-actions github-actions Bot added the pkg:OpenTelemetry.Extensions.Propagators Issues related to OpenTelemetry.Extensions.Propagators NuGet package label Apr 25, 2026
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codecov Bot commented Apr 25, 2026 •
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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.08%. Comparing base (8bee1f4) to head (e7514a2).
✅ All tests successful. No failed tests found.

Additional details and impacted files

Impacted file tree graph

@@            Coverage Diff             @@
##             main    #7171      +/-   ##
==========================================
- Coverage   89.10%   89.08%   -0.03%     
==========================================
  Files         271      271              
  Lines       13042    13063      +21     
==========================================
+ Hits        11621    11637      +16     
- Misses       1421     1426       +5
Flag Coverage Δ
unittests-Project-Experimental 88.67% <100.00%> (-0.29%) ⬇️
unittests-Project-Stable 89.08% <100.00%> (-0.01%) ⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines Coverage Δ
...lemetry.Extensions.Propagators/JaegerPropagator.cs 96.03% <100.00%> (+0.79%) ⬆️

... and 2 files with indirect coverage changes

@martincostello martincostello marked this pull request as ready for review April 25, 2026 20:36
@martincostello martincostello requested a review from a team as a code owner April 25, 2026 20:36
Copilot AI review requested due to automatic review settings April 25, 2026 20:36
Copilot AI reviewed Apr 25, 2026
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Pull request overview

This PR aims to improve JaegerPropagator extraction performance on modern .NET by optimizing how the propagator splits the uber-trace-id header into components.

Changes:

  • Adds a .NET-specific fast-path for parsing header components using SearchValues<char> + IndexOfAny.
  • Introduces a cached delimiter hint set (: and %) for faster delimiter discovery.
  • Keeps the existing parsing implementation for non-.NET TFMs via conditional compilation.

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Comment thread src/OpenTelemetry.Extensions.Propagators/JaegerPropagator.cs
@martincostello
[Propagators] Address feedback
966f508 
Do not silently scan past `%`.
@cijothomas
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cijothomas commented Apr 25, 2026

Given the component is to be deprecated, should we do perf improvements for it?

@martincostello
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martincostello commented Apr 26, 2026

This was "free" as part of some performance investigation work I asked Copilot to do. I figured they were worth keeping rather than throwing away as we still ship this anyway.

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cijothomas commented Apr 26, 2026

This was "free" as part of some performance investigation work I asked Copilot to do. I figured they were worth keeping rather than throwing away as we still ship this anyway.

I don't think this is "free". While copilot did a lot of heavy lifting, the review cycle isn't free for us — approver bandwidth is one of our biggest bottlenecks across OTel repos. I'd rather we save that energy for higher-impact work, like accelerating the deprecation/removal of this component.

Let's not make it harder for users to say goodbye to JaegerPropagator by making it faster! 🤣

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martincostello commented Apr 26, 2026

If it had been a large change, I would have likely agreed, but for ~50 lines I considered it worth the improvement considering we still ship this package and it's mostly just adopting some newer APIs from .NET itself.

rajkumar-rangaraj
rajkumar-rangaraj approved these changes Apr 27, 2026
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I want to acknowledge @cijothomas's point. Approver bandwidth across the OTel repos is tight right now, and I agree we should be prioritizing the higher-impact items.

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martincostello commented Apr 27, 2026

Next time I get Copilot to do some speculative search for improvements, I'll make sure I tell it to exclude any areas marked as deprecated.

@martincostello martincostello added this pull request to the merge queue Apr 27, 2026
Merged via the queue into open-telemetry:main with commit ad7412c Apr 27, 2026
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@martincostello martincostello deleted the JaegerPropagator-perf branch April 27, 2026 20:00
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