[efficiency-improver] Monthly Activity 2026-06

[Evangelink]

Activity for June 2026

Suggested Actions for Maintainer

• Review draft PR #aw_pr_derives: perf: eliminate LINQ iterator allocations in DerivesFrom() interface check — replaces OfType<ITypeSymbol>() + optional Select() + Contains() with a direct foreach over ImmutableArray<INamedTypeSymbol> (struct enumerator, zero heap allocation). Called via Inherits() 36+ times per symbol analysis pass. - Review
• Check comment on Expose programmatic test filtering via ITestFilter (avoid ClassInit cost for filtered-out tests) #8894: Efficiency Improver added energy-efficiency framing for ITestFilter — ClassInit waste quantification, TestFilterContext design note, measurement suggestion, GSF Demand Shaping reference. - View
• Check comment on [RFC] Agent/LLM-efficient test output for Microsoft.Testing.Platform #8824: Efficiency Improver added energy impact prioritisation for LLM-output RFC proposals — ordered by token reduction, stack-frame filtering highlighted as highest win, suggestion to track output byte count as CI health metric. - View

(Previous efficiency PRs #8692–#9436 are all merged — nothing else pending.)

Energy Efficiency Backlog

Priority	Focus Area	Opportunity	Estimated Impact
MEDIUM	Infrastructure	Assess benchmark coverage for IPC/reporter serializer paths; propose benchmarks if absent	Enables future regression detection
LOW	Code-Level	VideoRecorder: Properties.OfType<TestNodeStateProperty>().FirstOrDefault() → SingleOrDefault<TestNodeStateProperty>()	Rarely-used extension, minor
LOW	Code-Level	OpenTelemetry: Properties.OfType<TestMetadataProperty>() in yield iterator method — needs refactor to use non-iterator helper	Minor
LOW	Code-Level	TerminalTestReporter.cs:68 — TotalTests property calls _assemblies.Values.Sum() on every access; callers are rare	Negligible
LOW	Code-Level	ToolsTestHost.cs:55 — GroupBy().Where(Count()>1) at startup only	Negligible

Discovered Commands

Command	Purpose	Validated
./build.sh	Full restore + build	✅
./build.sh -test	Run unit tests	✅
./build.sh -pack	Build + produce NuGet packages	✅
./build.sh -pack -test -integrationTest	Full pipeline incl. acceptance tests	✅

Notes:

• Local SDK: .dotnet/dotnet (Arcade-provisioned; do not use /usr/bin/dotnet for SDK commands)
• --no-restore flag is broken (unknown MSBuild switch); always run with full restore
• MSTestAdapter internal-framework tests are not run by the MTP runner; CI covers them separately

Run History

2026-06-26 22:03 UTC - Run

• ✅ Confirmed PR [efficiency-improver] perf: direct-allocate arrays in IPC CommandLineOption and FileArtifact deserializers #9436 merged (efficiency/direct-array-alloc-remaining-ipc-serializers: direct-allocate arrays in IPC CommandLineOptionMessages and FileArtifactMessages) — IPC serializer series complete
• 🔍 Scanned src/Analyzers/MSTest.Analyzers/ for hot-path inefficiencies; found DerivesFrom() in ITypeSymbolExtensions.cs using OfType<ITypeSymbol>() + optional Select() + Contains() LINQ chain — each operator allocates a heap iterator state machine; called ~36+ times per symbol analysis pass
• 🔧 Submitted draft PR #aw_pr_derives: eliminate LINQ iterator allocations in DerivesFrom() — replace 1–2 heap iterators per call with direct foreach over ImmutableArray<INamedTypeSymbol> (struct enumerator)
• 📊 Proxy metric: managed heap allocation count per Roslyn analyzer invocation; ImmutableArray<T> struct enumerator avoids all iterator state-machine allocations
• 🌱 GSF principle: Hardware Efficiency (struct enumerator → fewer virtual dispatch calls) + SCI (fewer allocations per analysis pass across millions of MSTest projects in the .NET ecosystem)

2026-06-25 22:11 UTC - Run

• ✅ Confirmed PR [efficiency-improver] perf: direct-allocate arrays in IPC TestResultMessages deserializer #9408 merged (efficiency/direct-array-alloc-ipc-serializer: direct-allocate arrays in TestResultMessagesSerializer)
• 🔍 Scanned all remaining IPC serializers; found CommandLineOptionMessagesSerializer and FileArtifactMessagesSerializer still using List + [.. spread] pattern; TestInProgressMessagesSerializer was already correct; TestSessionEventSerializer has no lists; HandshakeMessageSerializer uses Dictionary
• 🔧 Submitted draft PR [efficiency-improver] perf: direct-allocate arrays in IPC CommandLineOption and FileArtifact deserializers #9436: direct-allocate arrays in CommandLineOptionMessages and FileArtifactMessages deserializers — completes the IPC serializer series (all 6 serializers now use direct T[length] allocation)
• 📊 Proxy metric: managed allocation count + O(N) array-copy operations eliminated per IPC session
• 🌱 GSF principle: Hardware Efficiency (pre-sized arrays avoid List backing-array reallocations) + SCI (fewer allocations per dotnet test run)

2026-06-24 22:04 UTC - Run

• ✅ Confirmed PR [efficiency-improver] perf: single-pass PropertyBag collection in DotnetTestDataConsumer #9380 merged (efficiency/single-pass-dotnet-test-consumer: single-pass PropertyBag collection in DotnetTestDataConsumer)
• 🔍 Scanned src/Adapter/ and src/TestFramework/ for new opportunities; found TestResultMessagesSerializer using List + [.. spread] instead of direct array allocation (unlike sibling DiscoveredTestMessagesSerializer which already does it right)
• 🔧 Submitted draft PR [efficiency-improver] perf: direct-allocate arrays in IPC TestResultMessages deserializer #9408: direct-allocate arrays in IPC TestResultMessagesSerializer — 3 List allocations + 3 [.. list] spreads → 3 pre-sized direct arrays
• 📊 Proxy metric: managed allocation count + O(N) array-copy operations per result batch
• 💬 Commented on Expose programmatic test filtering via ITestFilter (avoid ClassInit cost for filtered-out tests) #8894 (ITestFilter): energy framing, ClassInit waste quantification, GSF Demand Shaping reference
• 💬 Commented on [RFC] Agent/LLM-efficient test output for Microsoft.Testing.Platform #8824 (LLM-efficient output RFC): energy-impact prioritisation table, stack-frame filtering highlighted as largest token-reduction win, output-byte-count CI metric suggestion
• 🌱 GSF principle: Hardware Efficiency (fewer allocations per dotnet test run) + Demand Shaping (LLM output volume reduction)

2026-06-23 UTC - Run

• ✅ Confirmed PR [efficiency-improver] perf: single-pass aggregation in AppendTestRunSummary #9353 merged (efficiency/single-pass-summary-aggregation: single-pass LINQ aggregation in AppendTestRunSummary)
• 🔍 Scanned DotnetTestDataConsumer.cs: found 2 extra OfType() PropertyBag walks (FileArtifactProperty + TestMetadataProperty) on top of existing GetStructEnumerator pass
• 🔧 Submitted draft PR [efficiency-improver] perf: single-pass PropertyBag collection in DotnetTestDataConsumer #9380: consolidate FileArtifactProperty and TestMetadataProperty into existing single-pass GetStructEnumerator walk — eliminates 50–67% of PropertyBag iterations per test in dotnet-test server mode
• 📊 Proxy metric: PropertyBag linked-list iteration count (2–3× passes → 1× per test update)
• 🌱 GSF principle: Hardware Efficiency — fewer memory dereferences per test = lower instruction count

2026-06-22 22:21 UTC - Run

• 🔍 Task 4: Verified no open efficiency-improver PRs — previous efficiency/fix-parseoption-hot-loops branch was never pushed; CommandLineParseResult.cs already has the optimized code in main
• 🔍 Task 2: Scanned for new opportunities; confirmed PropertyBag hot-paths fully optimized across all report extensions; found 7-pass LINQ aggregation in AppendTestRunSummary (TerminalTestReporter.Summary.cs)
• 🔧 Submitted draft PR [efficiency-improver] perf: single-pass aggregation in AppendTestRunSummary #9353 (efficiency/single-pass-summary-aggregation): replace 7 separate LINQ calls (Sum×5, Any×1, Count×1) with single foreach — saves 6 extra passes + 6 LINQ enumerator allocations per end-of-run summary render
• 📊 Proxy metric: LINQ enumerator allocation count + iteration count at test-run end
• 🌱 GSF principle: Hardware Efficiency — fewer managed allocations per run reduces GC pressure

Earlier runs (2026-06-15 to 2026-06-21)

• PRs [perf-improver] perf: single-pass PropertyBag walk in TerminalOutputDevice and SimplifiedConsoleOutputDeviceBase #9159, [efficiency-improver] perf: single-pass PropertyBag walk in DiscoveredTestsJsonSerializer #9162, [efficiency-improver] perf: defer GetTestName() to failure branches and avoid OfType<> alloc in AzureDevOpsReporter #9196, [efficiency-improver] perf: single-pass GroupBy partition in TestExecutionManager parallelization #9274, [efficiency-improver] perf: avoid GroupBy lazy evaluation for empty-check in AppendTestRunSummary #9300 — all merged
• Focus: PropertyBag single-pass walks, GroupBy optimizations, AzureDevOps deferred GetTestName()

Earlier runs (2026-06-01 to 2026-06-14)

• PRs [efficiency-improver] perf: reduce redundant UTF-8 encoding in IPC BaseSerializer WriteField #8692–[efficiency-improver] perf: single-pass PropertyBag walk in JUnitReport TestResultCapture #9018 — all merged
• Focus: UTF-8 encoding, IPC serialization, TRX/OTel/TrxReport/AzureDevOps/SerializerUtilities PropertyBag walks, AnsiTerminal string caching

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