Daily Perf Improver: Set up BenchmarkDotNet for systematic benchmarking

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Summary

This PR establishes the foundational infrastructure for systematic performance benchmarking using BenchmarkDotNet, addressing Round 1 goals from the performance improvement plan (Issue #190).

Performance Improvements

🎯 Foundation Established:

• Before: No systematic benchmarking infrastructure
• After: Comprehensive BenchmarkDotNet setup with core benchmarks

📊 Benchmark Coverage:

• ✅ Core operations (unfoldAsync, replicate, mapAsync, chooseAsync)
• ✅ Append operations (tests for memory leak regression from Issue Memory leak when unfolding #35)
• ✅ Builder patterns (tests for O(n²) regression from Issue Unexpected iteration performance drop when recursive loops are used. #57)
• ✅ Memory diagnostics enabled for all benchmarks

Technical Implementation

New Benchmark Project

• Created tests/FSharp.Control.AsyncSeq.Benchmarks/ with proper .NET 8.0 console app setup
• Separate executable project for BenchmarkDotNet requirements
• Comprehensive benchmark suites targeting known performance issues

Benchmark Categories

1. Core Operations: Baseline performance for fundamental operations
2. Append Operations: Monitor for memory leaks (Issue Memory leak when unfolding #35 regression detection)
3. Builder Patterns: Monitor for O(n²) behavior (Issue Unexpected iteration performance drop when recursive loops are used. #57 regression detection)

Usage

# Run all benchmarks
dotnet run --project tests/FSharp.Control.AsyncSeq.Benchmarks -c Release

# Run specific suite  
dotnet run --project tests/FSharp.Control.AsyncSeq.Benchmarks -c Release -- core
dotnet run --project tests/FSharp.Control.AsyncSeq.Benchmarks -c Release -- append
dotnet run --project tests/FSharp.Control.AsyncSeq.Benchmarks -c Release -- builder

Validation

✅ All existing tests pass (175/175)
✅ BenchmarkDotNet infrastructure validated - successfully builds and runs
✅ Proper memory diagnostics enabled for detecting allocation issues
✅ No performance regressions introduced by infrastructure changes

Test Plan

• Run full test suite: dotnet test -c Release
• Build benchmark project: dotnet build tests/FSharp.Control.AsyncSeq.Benchmarks -c Release
• Validate benchmark execution: dotnet run --project tests/FSharp.Control.AsyncSeq.Benchmarks -c Release
• Verify memory diagnostics work correctly
• Test benchmark suite selection (core, append, builder, all)

Related Issues

• Addresses Round 1 foundation goal from Daily Perf Improver: Research and Plan #190 (Performance Research and Plan)
• Enables future detection of regressions for Issues Memory leak when unfolding #35, Unexpected iteration performance drop when recursive loops are used. #57, AsyncSeq.append called enormous number of times #50, Parallel sequence runs consequentially (non-parallel) #74, Lack of parallelism in AsyncSeq.cache #95
• Establishes baseline metrics for all future performance improvements

Commands Used

# Project setup and package installation
dotnet add tests/FSharp.Control.AsyncSeq.Tests package BenchmarkDotNet --version 0.14.0
mkdir -p tests/FSharp.Control.AsyncSeq.Benchmarks

# Build and validation
dotnet build tests/FSharp.Control.AsyncSeq.Benchmarks -c Release
dotnet test -c Release

# Benchmark execution testing
dotnet run --project tests/FSharp.Control.AsyncSeq.Benchmarks -c Release

# Branch management  
git checkout -b daily-perf-improver/benchmarkdotnet-setup
git add . && git commit
git push -u origin daily-perf-improver/benchmarkdotnet-setup

Web Searches Performed

• None required - used existing BenchmarkDotNet documentation and performance research from Issue Daily Perf Improver: Research and Plan #190

MCP Function Calls Used

• mcp__github__search_issues: Found research issue Daily Perf Improver: Research and Plan #190 and related performance issues
• mcp__github__get_issue: Retrieved details for issues Memory leak when unfolding #35, Unexpected iteration performance drop when recursive loops are used. #57, Parallel sequence runs consequentially (non-parallel) #74, Lack of parallelism in AsyncSeq.cache #95
• mcp__github__search_pull_requests: Verified no conflicting performance PRs
• mcp__github__list_pull_requests: Checked for existing performance work

This establishes the critical foundation for all future performance work, enabling systematic measurement, regression detection, and optimization validation. Future performance improvements can now be measured accurately with statistical rigor using BenchmarkDotNet.

🤖 Generated with Claude Code