[Perf Improver] Monthly Activity 2026-05

[Evangelink]

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Activity for May 2026

Suggested Actions for Maintainer

• Close duplicate issues: [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #7992, [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #7993, [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #8000, [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #8016, [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #8028, [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #8044, [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #8055, [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #8067, [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #8075 — all covered by merged PR [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #8095
• Close issue [Perf Improver] perf: reduce allocations in test discovery and data-driven test execution #7815: Changes (ValidSourceExtensions cache + ReflectionTestMethodInfo dedup) confirmed applied to main - View
• Close issue [Perf Improver] perf: avoid yield iterator allocations in test execution hot path #7904: Maintainers confirmed allocations not visible in profiler traces; branch can be discarded - View

Performance Opportunities Backlog

1. [Applied to main ✅] ValidSourceExtensions static cache + ReflectionTestMethodInfo deduplication
2. [Applied to main ✅] Eliminate LINQ iterator allocations in TryUnfoldITestDataSources
3. [Merged ✅ PR [Perf Improver] perf: eliminate LINQ iterator allocations in GetTestCategories and GetTestFromMethod #7927] Eliminate LINQ iterators in GetTestCategories + WorkItemAttribute double-pass + parameterless method short-circuit
4. [Merged ✅ PR [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #8095 - 2026-05-13] Eliminate LINQ allocations in IsIgnored (~4 objects per test execution, common case 0)
5. [Deprioritized - no profiler evidence] Avoid yield iterator in TryExecuteDataSourceBasedTestsAsync + GetRetryAttribute (issue [Perf Improver] perf: avoid yield iterator allocations in test execution hot path #7904)
6. TreeNodeFilter LINQ closure allocations — covered by Efficiency Improver ([Efficiency Improver] perf: eliminate LINQ closure allocations in TreeNodeFilter.MatchFilterPattern and MatchProperties #7947, [Efficiency Improver] perf: eliminate LINQ closure allocations in TreeNodeFilter hot paths #7974, [Efficiency Improver] perf: eliminate LINQ closure allocations in TreeNodeFilter #8035)
7. SynchronizedStringBuilder in TestContextImplementation uses [MethodImpl(Synchronized)]; requires profiler evidence before implementing

(No new high-confidence targets found in discovery/execution/helpers scans. Continuing to monitor.)

Discovered Commands

• Build (Linux/macOS): export PATH="$PWD/.dotnet:$PATH" && dotnet restore && dotnet build -f net8.0
• Pre-existing infrastructure issue: MSTest.TestAdapter.csproj build fails due to missing ApplicationInsights NuGet (unrelated to test framework code)
• Targeting packs available: net8.0, net9.0 (after restore); net462/NETFRAMEWORK not available in sandbox
• Performance runner: test/Performance/MSTest.Performance.Runner/ (all pipelines currently Windows-only — DotnetTrace step is cross-platform-ready but pipeline registration restricts to Windows)

Run History

2026-05-13 16:18 UTC - Run

• ✅ Task 4: PR [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #8095 merged by Evangelink on 2026-05-13 🎉 — IsIgnored LINQ allocation elimination landed
• 🔍 Task 2: Quick scan of discovery/execution paths — no new high-confidence targets found
• 📋 Task 7: Updated monthly activity summary

2026-05-12 13:19 UTC - Run

• 🔧 Task 4: Fixed Windows CI failure in PR [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #8095 — restored ConfigureAwait(true) (intentional for WinUI) and BOM in resource file
• 📋 Task 7: Updated monthly activity summary

2026-05-10 13:19 UTC - Run

• 🔍 Task 4: No open [Perf Improver] PRs — nothing to maintain
• 🔍 Task 6: Assessed performance runner infrastructure — all pipelines are Windows-only; DotnetTrace step itself is cross-platform (already handles Linux exe name) but pipelines haven't been updated
• 📋 Task 7: Updated monthly activity summary

2026-05-09 13:19 UTC - Run

• 🔧 Task 3: Re-implemented IsIgnored LINQ allocation elimination (9th attempt). Resolved SA1316 by replacing named tuples with two separate dictionaries. Build: 0 warnings, 0 errors. Patch posted as comment on [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #7992 (run 25602028457).
• 💬 Task 5: Added patch to [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #7992 with git am instructions for maintainers
• 📋 Task 7: Updated monthly activity summary

2026-05-08 13:20 UTC - Run

• 🔧 Task 3: Implemented IsIgnored LINQ allocation elimination (8th attempt). Build: 0 warnings, 0 errors.
• 📋 Task 7: Updated monthly activity summary

2026-05-07 13:25 UTC - Run

• 🔧 Task 3: Implemented IsIgnored LINQ allocation elimination (7th attempt). Build: 0 warnings, 0 errors.
• 📋 Task 7: Updated monthly activity summary

2026-05-06 13:25 UTC - Run

• 🔧 Task 3: Re-implemented IsIgnored LINQ allocation elimination (6th attempt). Build: 0 warnings, 0 errors.
• 🔍 Task 2: Scanned Execution/, Discovery/, Helpers/ for remaining LINQ hot-path allocations — no new high-confidence targets found beyond existing backlog.
• 📋 Task 7: Updated monthly activity summary

2026-05-05 13:20 UTC - Run

• 🔧 Task 3: Re-implemented IsIgnored LINQ allocation elimination (5th attempt). Build: 0 warnings, 0 errors.
• 💬 Task 5: Commented on Track perf over time #6326 (Track perf over time) — suggested allocation-focused scenarios and BDN regression detection thresholds
• 📋 Task 7: Updated monthly activity summary

2026-05-04 13:22 UTC - Run

• 🔧 Task 3: Re-implemented IsIgnored LINQ allocation elimination (4th attempt). Build: 0 warnings, 0 errors.
• 🔍 Task 2: Investigated new opportunities — no high-confidence new targets found.
• 📋 Task 7: Updated monthly activity summary

2026-05-03 13:18 UTC - Run

• 🔧 Task 3/4: Re-implemented IsIgnored LINQ allocation optimization. Build: 0 warnings, 0 errors.
• 📋 Task 7: Updated monthly activity summary

2026-05-02 13:19 UTC - Run

• 🔧 Task 3: Implemented IsIgnored LINQ allocation optimization — Created issues [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #7992 and [Perf Improver] perf: eliminate LINQ allocations in IsIgnored hot path #7993 as placeholders.
• 📋 Task 7: Updated monthly activity summary

2026-05-01 13:20 UTC - Run

• ✅ Task 4: PR [Perf Improver] perf: eliminate LINQ iterator allocations in GetTestCategories and GetTestFromMethod #7927 confirmed merged by Evangelink on 2026-04-30 — no open Perf Improver PRs
• 🔍 Task 2: Explored new opportunities — SynchronizedStringBuilder identified but needs profiler evidence; TreeNodeFilter covered by Efficiency Improver
• 📋 Task 7: Closed April 2026 monthly issue; opened May 2026 monthly issue

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