🤖 Perf Improver here - I'm an automated AI assistant focused on performance improvements for this repository.

Activity for June 2026

Suggested Actions for Maintainer

• Review draft PR perf-assist/cache-generate-lines-buffers: Eliminate 5 per-tick allocations in GenerateLinesToRender via cached buffers (~12,000 allocs eliminated per 5-min run) — PRs

Performance Opportunities Backlog

1. GenerateLinesToRender List<object> heterogeneous boxing — consider a sealed base type to avoid type checks; lower priority
2. TestNodeResultsState.GetRunningTasks() — still allocates a new List<TestDetailState> per assembly per tick; could be cached similarly

Discovered Commands

• Build: ./build.sh -build -c Debug (Linux)
• Full build (all TFMs): ./build.sh
• Run platform unit tests: artifacts/bin/Microsoft.Testing.Platform.UnitTests/Debug/net8.0/Microsoft.Testing.Platform.UnitTests
• Profiling infrastructure: test/Performance/MSTest.Performance.Runner — uses dotnet-trace, PerfView, VSDiagnostics, ConcurrencyVisualizer
• Note: system dotnet is a stub; build.sh installs pinned SDK into .dotnet/

Run History

2026-06-10 14:52 UTC - Run

• ✅ PR [perf-improver] perf: cache ANSI cursor-positioning strings in AnsiTerminalTestProgressFrame hot path #8970 (perf-assist/cache-ansi-cursor-sequences) — MERGED by Evangelink
• 🔧 Created draft PR perf-assist/cache-generate-lines-buffers: cache GenerateLinesToRender working buffers — eliminates 5 allocs/tick (4 collections + sort closure), ~12,000 eliminated per 5-min run
• ✅ Tests: 1107 passed, 0 failed, 0 warnings

2026-06-09 14:21 UTC - Run

• ✅ PR [perf-improver] perf: add GetLongestRunningTask to avoid list allocation in SimpleTerminal #8932 (GetLongestRunningTask O(n) scan for SimpleTerminal) — MERGED by Evangelink
• 🔍 Task 2: Identified new hot-path opportunity in AnsiTerminalTestProgressFrame.Render() duration-only path
• 🔧 Created PR perf-assist/cache-ansi-cursor-sequences: cache ANSI cursor-positioning strings — 4 allocs → 0 per item per tick, ~24 000 eliminations per 5-min run

2026-06-08 14:47 UTC - Run

• 🔧 Created PR: perf: add GetLongestRunningTask to avoid list allocation in SimpleTerminal — O(n log n) sort + List alloc → O(n) scan, ~6 000 allocs eliminated per 5-min run
• 📋 Task 4: No open perf-improver PRs (all merged by Evangelink)
• 🔍 Task 6: Assessed measurement infrastructure — test/Performance/MSTest.Performance.Runner exists with dotnet-trace/PerfView profiling; no BenchmarkDotNet microbenchmarks present

2026-06-06 14:09 UTC - Run

• 🔧 Created PR [perf-improver] perf: reuse AnsiTerminalTestProgressFrame across render ticks via double-buffer swap #8883: Reuse AnsiTerminalTestProgressFrame via double-buffer swap (~3 000 allocs/5-min run eliminated) — MERGED 2026-06-07

2026-06-05 14:xx UTC - Run

• 🔧 Created PR [perf-improver] perf: fast path in HumanReadableDurationFormatter.Render for sub-hour durations #8861: Fast path in HumanReadableDurationFormatter.Render (3–4 allocs → 1 per call) — MERGED 2026-06-07

Earlier runs (merged PRs)

• PR [perf-improver] perf: add GetLongestRunningTask to avoid list allocation in SimpleTerminal #8932: GetLongestRunningTask() O(n) scan for SimpleTerminal.RenderProgress — MERGED 2026-06-09
• PR [perf-improver] perf: single-pass message iteration in VSTestBridge ObjectModelConverters #8823: single-pass message iteration in VSTestBridge ObjectModelConverters — MERGED 2026-06-05
• PR [perf-improver] perf: eliminate LINQ allocations in terminal progress render hot path #8799: eliminate LINQ allocations in terminal progress render hot path — MERGED
• PR [perf-improver] perf: eliminate string allocations in ANSI render hot path #8769: eliminate string allocations in ANSI render hot path — MERGED
• PR [perf-improver] perf: eliminate per-call string allocation in AnsiTerminal.SetColor and use HashSet for KnownFileExtensions #8739: eliminate per-call string allocation in AnsiTerminal.SetColor + HashSet for KnownFileExtensions — MERGED
• PR [perf-improver] perf: cache distinct processors in AsynchronousMessageBus to eliminate per-drain allocation #8704: cache distinct processors in AsynchronousMessageBus — MERGED
• PR [perf-improver] perf: replace Regex array in AnsiDetector with direct string comparisons #8683: replace Regex array in AnsiDetector with direct string comparisons — MERGED

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