Compare ArrayPool and ConfigurableArrayPool from .NET 5 - Complete Analysis

[konard]

Summary

Comprehensive analysis comparing Platform.Collections.ArrayPool with .NET's ConfigurableArrayPool addressing performance, memory leaks, and thread safety as requested in issue #101.

Key Findings

Performance Comparison

• Single-threaded: Platform.Collections.ArrayPool is faster (zero synchronization overhead)
• Multi-threaded: ConfigurableArrayPool may perform better (shared resource utilization)
• High contention: Platform.Collections.ArrayPool avoids lock contention entirely

Memory Leak Analysis

• Platform.Collections.ArrayPool: Higher risk due to thread-static isolation
• ConfigurableArrayPool: Lower risk with centralized management and monitoring
• Both: Handle pool overflow by discarding arrays (no infinite growth)

Thread Safety

• Platform.Collections.ArrayPool: Thread-safe via per-thread isolation (ThreadStatic)
• ConfigurableArrayPool: Thread-safe via SpinLock with resource sharing
• Both: Verified safe under high concurrency (20 threads, 10k+ operations)

Implementation

Added Files

• ConfigurableArrayPool.cs - Simplified .NET ConfigurableArrayPool implementation
• ArrayPoolBenchmarks.cs - Performance comparison benchmarks
• ArrayPoolThreadSafetyTests.cs - Comprehensive thread safety tests
• experiments/ArrayPool_Comparison_Report.md - Detailed analysis report

Test Results

✅ All thread safety tests pass
✅ Memory leak tests show acceptable growth
✅ Concurrent access stress tests (20 threads × 500 operations) pass

Recommendations

Choose Platform.Collections.ArrayPool for:

• High-performance single-threaded scenarios
• Applications requiring zero synchronization overhead
• Simple, predictable per-thread behavior

Choose ConfigurableArrayPool for:

• Multi-threaded applications with resource constraints
• Applications requiring centralized pool monitoring
• Scenarios where cross-thread resource sharing is beneficial

How to Run

# Run benchmarks
cd csharp
dotnet run --project Platform.Collections.Benchmarks -c Release

# Run thread safety tests
dotnet test Platform.Collections.Tests --filter "ArrayPoolThreadSafetyTests"

Fixes #101

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