[perf-improver] Monthly Activity 2026-06

[Evangelink]

Activity for June 2026

Suggested Actions for Maintainer

• Review PR [perf-improver] perf: add dotnet test server-mode scenario to performance runner #9486: add dotnet test server-mode scenario to performance runner — Review
• Review PR #aw_pr_new: avoid List<TestResult> allocation in RunTestMethodAsync non-data-driven fast path — Review
• Close issue [perf-improver] perf: add Linux parallel job to nightly perf-timing workflow #9399: work completed by PR [perf-improver] perf: add Linux job to nightly perf-timing workflow #9450 (Linux perf-timing job, merged 2026-06-26) — View

Performance Opportunities Backlog

1. [Done ✅ PR [perf-improver] perf: single-pass PropertyBag walk in TerminalOutputDevice and SimplifiedConsoleOutputDeviceBase #9159 merged] Single-pass PropertyBag walk in TerminalOutputDevice / SimplifiedConsoleOutputDeviceBase
2. [Done ✅ PR [perf-improver] perf: replace per-test Queue/Stack copies with List-based index iteration in TestMethodInfo lifecycle #9257 merged] Eliminate per-test Queue / Stack allocation in MSTest adapter lifecycle
3. [Done ✅ PR [perf-improver] Replace Array.IndexOf(GetType()) with 'is' pattern matching in hot paths #9299 merged] Replace Array.IndexOf(GetType()) with is pattern matching in TestApplicationResult, AbortForMaxFailedTestsExtension, RetryDataConsumer
4. [Done ✅ PR [perf-improver] Extend performance runner timing scenarios to Linux/macOS and add ClassLevel variant #9311 merged] Extend performance runner timing scenarios to Linux/macOS; add ClassLevel variant
5. [Done ✅ PR [perf-improver] perf: avoid redundant TestNodeUid allocation in PopulateTestNodeStatistics #9348 merged] Avoid redundant TestNodeUid allocation in PerRequestServerDataConsumer.PopulateTestNodeStatistics (server mode, 2×N per test run)
6. [Done ✅ PR [perf-improver] perf: skip unused TestContextImplementation allocations for repeat assembly/class init #9433 merged] Skip unused TestContextImplementation allocations in UnitTestRunner.RunSingleTestAsync: for tests 2+ in an assembly/class, ~2 dictionary copies + 2 CancellationTokenRegistration allocs skipped per test
7. [Done ✅ PR [perf-improver] perf: add Linux job to nightly perf-timing workflow #9450 merged] Add Linux job to nightly perf-timing workflow
8. [Done ✅ PR [perf-improver] perf: defer class-cleanup TestContextImplementation allocation to last test in class #9461 merged] Defer class-cleanup TestContextImplementation allocation to last test only — saves C×(K−1) allocations for C classes averaging K tests each
9. [Done ✅ PR [perf-improver] perf: skip allocation in CaptureLifecycleProperties when no user properties set #9478 merged] Skip Dictionary + ReadOnlyDictionary allocation in CaptureLifecycleProperties when init method sets no properties (common case); also skip MergeProperties lock acquisition per test
10. [PR [perf-improver] perf: add dotnet test server-mode scenario to performance runner #9486 open] Add DotnetTestProcess step + Scenario1_DotnetTest_PlainProcess pipeline to measure MTP server-mode (JSON-RPC / named-pipe) timing; auto-captured by existing *PlainProcess* nightly filter (addresses [efficiency-improver] Add server-mode (JSON-RPC) performance scenario to nightly perf pipeline #9480)
11. [PR #aw_pr_new open] Avoid List<TestResult> allocation in RunTestMethodAsync non-data-driven fast path — single combined attribute scan replaces 2 separate scans; ~3 heap allocations saved per non-data-driven test
12. AntiTerminal.StopUpdate() — _stringBuilder.ToString() allocates on every terminal-output flush; blocked on IConsole interface limitation (netstandard2.0 target). Low priority.
13. SilenceDrivenHeartbeatRenderer — allocations only on rare heartbeat/slow-test paths; not a hot path. Low priority.
14. ClassifyOutcome in TestResultCaptureHelper.cs — add explicit CancelledTestNodeStateProperty arm to avoid Array.IndexOf fallback for obsolete type. Very low priority.

Discovered Commands

# Build all projects (Debug)
./build.sh

# Build + run unit tests
./build.sh -test

# Pack NuGet packages (required before acceptance tests and performance runner)
./build.sh -pack

# Run acceptance integration tests (requires -pack first)
./build.sh -pack -test -integrationTest

# Run performance timing scenarios (requires -pack first)
.dotnet/dotnet run --project test/Performance/MSTest.Performance.Runner \
  -- execute --pipelineNameFilter "*PlainProcess*"

# Run a single test project (using installed SDK in .dotnet/)
.dotnet/dotnet run --project <project-path> -f net9.0 --no-build -- --treenode-filter "*/*/MyTestClass/*"

Run History

2026-06-29 15:00 UTC - Run

• 📋 Task 4: Confirmed PR [perf-improver] perf: defer class-cleanup TestContextImplementation allocation to last test in class #9461 merged 2026-06-29 and PR [perf-improver] perf: skip allocation in CaptureLifecycleProperties when no user properties set #9478 merged 2026-06-28 by Evangelink ✅; PR [perf-improver] perf: add dotnet test server-mode scenario to performance runner #9486 open (only automated grade-test comments, no human action needed yet)
• 🔍 Task 2/3: Identified RunTestMethodAsync allocates List<TestResult> + spread array for every non-data-driven test (common case), plus performs 2 redundant attribute scans
• 🔧 Task 3: Submitted PR #aw_pr_new on branch perf-assist/skip-list-alloc-non-data-driven — avoid List<TestResult> allocation and 2-scan cost in non-data-driven fast path; ~3 heap allocations saved per test

2026-06-28 14:19 UTC - Run

• 📋 Task 4: PR [perf-improver] perf: skip allocation in CaptureLifecycleProperties when no user properties set #9478 CI all green ✅; PR [perf-improver] perf: defer class-cleanup TestContextImplementation allocation to last test in class #9461 Linux Debug failure unchanged (pre-existing flaky test, no new maintainer comments)
• 🔧 Task 6: Submitted PR [perf-improver] perf: add dotnet test server-mode scenario to performance runner #9486 on perf-assist/dotnet-test-server-mode-scenario — add DotnetTestProcess step and Scenario1_DotnetTest_PlainProcess pipeline to measure MTP server-mode (JSON-RPC / named-pipe) timing; auto-captured by existing *PlainProcess* nightly filter (addresses [efficiency-improver] Add server-mode (JSON-RPC) performance scenario to nightly perf pipeline #9480)
• 🔍 Task 5: Scanned performance issues — [perf-improver] perf: add Linux parallel job to nightly perf-timing workflow #9399 is stale (work done by merged PR [perf-improver] perf: add Linux job to nightly perf-timing workflow #9450); [efficiency-improver] Add server-mode (JSON-RPC) performance scenario to nightly perf pipeline #9480 was filed by efficiency-improver for server-mode scenario gap (addressed by this run's PR)

2026-06-27 UTC - Run

• 📋 Task 4: Analyzed Linux Debug CI failure in PR [perf-improver] perf: defer class-cleanup TestContextImplementation allocation to last test in class #9461 — code invariant is sound; failure is likely a pre-existing flaky test unrelated to the change
• 🔍 Task 2/3: Identified CaptureLifecycleProperties unconditionally allocates two objects (Dictionary + ReadOnlyDictionary) even when no user properties were set — the common case
• 🔧 Task 3: Submitted PR [perf-improver] perf: skip allocation in CaptureLifecycleProperties when no user properties set #9478 on branch perf-assist/avoid-empty-snapshot-alloc — skip allocations in CaptureLifecycleProperties when no non-label properties exist; null return avoids lock acquisition per test in MergeProperties

2026-06-26 15:00 UTC - Run

• 📋 Task 4: Confirmed PR [perf-improver] perf: skip unused TestContextImplementation allocations for repeat assembly/class init #9433 and PR [perf-improver] perf: add Linux job to nightly perf-timing workflow #9450 both merged 2026-06-26
• 🔍 Task 2/3: Scanned UnitTestRunner.cs hot paths — found testContextForClassCleanup allocated unconditionally for every test even when not used
• 🔧 Task 3: Submitted PR [perf-improver] perf: defer class-cleanup TestContextImplementation allocation to last test in class #9461 on branch perf-assist/defer-class-cleanup-context-alloc

2026-06-25 14:30 UTC - Run

• 🔧 Task 3: Submitted draft PR → MERGED as PR [perf-improver] perf: skip unused TestContextImplementation allocations for repeat assembly/class init #9433 on 2026-06-26
• 🔍 Task 2: Confirmed no new high-value targets beyond the submitted PR

2026-06-24 14:17 UTC - Run

• 🔍 Task 2: Surveyed hot paths — efficiency-improver covered DotnetTestDataConsumer ([efficiency-improver] perf: single-pass PropertyBag collection in DotnetTestDataConsumer #9380) same day
• 🔧 Task 6: Planned Linux perf-timing PR → created as PR [perf-improver] perf: add Linux job to nightly perf-timing workflow #9450 on 2026-06-26, MERGED same day

2026-06-23 UTC - Run

• 📝 Confirmed PR [perf-improver] perf: avoid redundant TestNodeUid allocation in PopulateTestNodeStatistics #9348 merged by Evangelink on 2026-06-23

2026-06-19 UTC - Run

• 🔧 Created PR [perf-improver] perf: avoid redundant TestNodeUid allocation in PopulateTestNodeStatistics #9348: Avoid redundant TestNodeUid allocation — MERGED 2026-06-23

2026-06-21 14:14 UTC - Run

• 🔧 Created PR [perf-improver] Extend performance runner timing scenarios to Linux/macOS and add ClassLevel variant #9311: Extend performance runner to Linux/macOS — MERGED 2026-06-22
• 📋 Created issue [perf-improver] Track performance regressions in CI: integrate MSTest.Performance.Runner timing output #9312: CI regression detection proposal — CLOSED (implemented by Evangelink in PR Add Phase 1 nightly perf-timing CI workflow (#9312) #9325)

2026-06-20 14:30 UTC - Run

• 🔧 Created PR [perf-improver] Replace Array.IndexOf(GetType()) with 'is' pattern matching in hot paths #9299: Replace Array.IndexOf(GetType()) with is pattern matching — MERGED 2026-06-22

2026-06-17 - Run

• 🔧 Created PR [perf-improver] perf: replace per-test Queue/Stack copies with List-based index iteration in TestMethodInfo lifecycle #9257: Replace per-test Queue/Stack with List-based index iteration — MERGED 2026-06-19

2026-06-15 - Run

• 🔧 Created PR [perf-improver] perf: single-pass PropertyBag walk in TerminalOutputDevice and SimplifiedConsoleOutputDeviceBase #9159: Single-pass PropertyBag walk in TerminalOutputDevice — MERGED 2026-06-16
• 🔍 Identified per-test Queue/Stack allocation as next target

🤖 Automated content by GitHub Copilot. Posted via a maintainer's GitHub token, so it appears under their account — the account owner did not write or approve this content personally. Generated by the Perf Improver workflow. · 1.7K AIC · ⌖ 26.2 AIC · ⊞ 57.7K · [◷]( · ◷)

Add this agentic workflows to your repo

To install this agentic workflow, run

gh aw add githubnext/agentics/workflows/perf-improver.md@main