Scalene Profiler Refactoring Plan

Goal

Refactor scalene/scalene_profiler.py into multiple files with clear separation of concerns.

Status: ✅ COMPLETE

All verification checks pass:

• pytest tests/ - 147 tests passed
• mypy scalene - No issues found
• ruff check scalene - All checks passed

File Sizes

Net reduction: ~300 lines from main profiler, with reusable logic extracted

New Modules Created

1. scalene_cpu_profiler.py ✅

• Class: ScaleneCPUProfiler
• Purpose: CPU profiling sample processing
• Key methods:
  • process_cpu_sample - Main CPU sample handler
  • _update_main_thread_stats - Main thread statistics
  • _update_thread_stats - Other thread statistics

2. scalene_tracing.py ✅

• Class: ScaleneTracing
• Purpose: Tracing decisions and file filtering with lru_cache
• Key methods:
  • should_trace - Main entry point (cached)
  • _passes_exclusion_rules - Library exclusions
  • _should_trace_by_location - Path-based filtering
  • _is_system_library - System library detection

3. scalene_lifecycle.py ✅

• Class: ScaleneLifecycle
• Purpose: Profiler lifecycle management (prepared for future use)

Architecture

scalene_profiler.py (Scalene class)
    ├── ScaleneCPUProfiler (CPU sample processing)
    ├── ScaleneTracing (file/function filtering)
    ├── ScaleneMemoryProfiler (already existed)
    └── ScaleneSignalManager (already existed)

Completed Tasks

• Extracted CPU profiling logic (~150 lines)
• Extracted tracing/filtering logic (~150 lines)
• Created lifecycle module for future use
• Updated type signatures to use Filename consistently
• Applied proper lru_cache usage
• All tests passing (147/147)
• Type checking passing (mypy)
• Linting passing (ruff)