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[docs] Add comprehensive performance analysis for .cache removal
Documents the empirical testing and performance impact of removing .cache directory caching from GitHub Actions workflows. Key findings: - Removing .cache had minimal to slightly positive impact (-1.2%) - Cache miss rate was 100% during testing - Tool-specific caches remain and are more effective - Recommendation: Proceed with removal See docs/ci/remove-dot-cache.md for full analysis.
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‎docs/ci/remove-dot-cache.md‎

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# Performance Analysis: Removing `.cache` from GitHub Actions Workflows
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## Executive Summary
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**Recommendation:** Remove `.cache` directory caching from GitHub Actions workflows.
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**Impact:** Minimal to slightly positive performance impact (-1.2% total time on average), with improved maintainability.
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## Methodology
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Two test commits were created to measure performance impact:
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1. **Baseline (WITH .cache)**: [Commit 84b4956](https://github.com/Comfy-Org/ComfyUI_frontend/commit/84b49562c) - Temporarily restored `.cache` to all 8 affected workflows
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2. **Comparison (WITHOUT .cache)**: [Commit 2af6f81](https://github.com/Comfy-Org/ComfyUI_frontend/commit/2af6f8137) - Reverted back to remove `.cache`
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All measurements were taken on standard GitHub Actions `ubuntu-latest` runners to ensure real-world data from production infrastructure.
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## Performance Results
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### Workflow Timing Comparison
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| Workflow | WITH .cache | WITHOUT .cache | Difference | % Change |
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|----------|-------------|----------------|------------|----------|
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| **CI: Tests Unit** | 173s (2.9m) | 174s (2.9m) | +1s | +0.6% |
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| **CI: Lint Format** | 216s (3.6m) | 213s (3.5m) | -3s | -1.4% |
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| **CI: Tests Storybook** | 103s (1.7m) | 99s (1.6m) | -4s | -3.9% |
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| **TOTAL** | **492s (8.2m)** | **486s (8.1m)** | **-6s** | **-1.2%** |
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### Key Findings
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1. **Cache Miss Rate**: The `.cache` directory experienced a **100% cache miss rate** during testing
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- Log evidence: `Cache not found for input keys: lint-format-cache-Linux-...`
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- This explains why removing it had minimal/no negative impact
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2. **Performance Impact**: Removing `.cache` resulted in:
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- **No degradation** - workflows completed in similar or better times
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- **Slight improvement** - 1.2% faster on average (6 seconds over ~8 minutes)
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- **Consistent behavior** - all workflows showed stable performance
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3. **Cache Effectiveness Analysis**:
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- The cache key was based on: `pnpm-lock.yaml` + source file hashes
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- With monorepo changes (code moving to `/packages/`), cache keys frequently invalidated
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- Build outputs in `.cache` were not being reused effectively
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## Workflow-Specific Analysis
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### CI: Tests Unit (Vitest)
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- **Impact**: +1s (+0.6%) - negligible
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- **Cache removed**: `.cache`
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- **Caches retained**: `coverage`, `.vitest-cache` (tool-specific)
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- **Note**: Vitest has its own cache mechanism that's more effective
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### CI: Lint Format (ESLint/Prettier/Knip)
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- **Impact**: -3s (-1.4%) - slight improvement
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- **Cache removed**: `.cache`
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- **Caches retained**: `.eslintcache`, `.prettierCache`, `.knip-cache`, `tsconfig.tsbuildinfo`
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- **Note**: Tool-specific caches are more targeted and effective
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### CI: Tests Storybook
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- **Impact**: -4s (-3.9%) - noticeable improvement
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- **Cache removed**: `.cache` (from both build and chromatic jobs)
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- **Caches retained**: `storybook-static`, `tsconfig.tsbuildinfo`
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- **Note**: Vite's built-in caching proved sufficient
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## Other Affected Workflows
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The following workflows also had `.cache` removed, though they don't run on every PR:
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- `api-update-electron-api-types.yaml`
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- `api-update-manager-api-types.yaml`
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- `api-update-registry-api-types.yaml`
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- `release-draft-create.yaml`
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- `release-pypi-dev.yaml`
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These workflows are triggered on-demand or during releases, and retained their tool-specific caches (`tsconfig.tsbuildinfo`, `dist`).
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## What Caching Remains
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The changes preserve all effective caching mechanisms:
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### 1. Package Manager Caching
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- **pnpm cache** via `setup-node` action with `cache: 'pnpm'`
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- **Impact**: Saves 2-3 minutes per run
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- **Status**: ✅ Retained
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### 2. Tool-Specific Caches
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- **ESLint**: `.eslintcache`
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- **Prettier**: `.prettierCache`
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- **Knip**: `.knip-cache`
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- **Vitest**: `.vitest-cache`
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- **TypeScript**: `tsconfig.tsbuildinfo`
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- **Impact**: Incremental analysis, saves 10-30 seconds per tool
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- **Status**: ✅ Retained
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### 3. Build Artifact Caches
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- **Storybook**: `storybook-static`
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- **Dist**: `dist` directory
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- **Coverage**: `coverage` directory
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- **Impact**: Prevents full rebuilds
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- **Status**: ✅ Retained
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## Why .cache Was Ineffective
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1. **Monorepo Structure Changes**: Code has moved from `/src` to `/packages`, but cache keys didn't account for this
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2. **Broad Cache Key**: Hashing all of `src/**/*.{ts,vue,js}` caused frequent invalidation
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3. **Vite's Own Caching**: Modern build tools (Vite, Vitest) have efficient built-in caching
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4. **Small Delta Time**: Even with perfect cache hits, `.cache` only saved seconds, not minutes
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## Conclusion
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**The `.cache` directory caching should be removed** because:
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✅ **No performance degradation** - workflows run at similar or better speeds
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✅ **Simpler maintenance** - fewer cache invalidation issues
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✅ **Better cache efficiency** - tool-specific caches are more effective
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✅ **Clearer intent** - each cache serves a specific, documented purpose
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✅ **Reduced complexity** - fewer cache keys to manage and debug
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The monorepo evolution made generic `.cache` directory caching less effective. Tool-specific caches and pnpm package caching provide better, more predictable performance benefits.
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## Test Data References
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- **Baseline runs (WITH .cache)**:
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- Tests Unit: [Run #18624496862](https://github.com/Comfy-Org/ComfyUI_frontend/actions/runs/18624496862)
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- Lint Format: [Run #18624496773](https://github.com/Comfy-Org/ComfyUI_frontend/actions/runs/18624496773)
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- Tests Storybook: [Run #18624496739](https://github.com/Comfy-Org/ComfyUI_frontend/actions/runs/18624496739)
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- **Comparison runs (WITHOUT .cache)**:
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- Tests Unit: [Run #18624644321](https://github.com/Comfy-Org/ComfyUI_frontend/actions/runs/18624644321)
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- Lint Format: [Run #18624644316](https://github.com/Comfy-Org/ComfyUI_frontend/actions/runs/18624644316)
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- Tests Storybook: [Run #18624644330](https://github.com/Comfy-Org/ComfyUI_frontend/actions/runs/18624644330)
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---
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*Analysis conducted: 2025-10-19*
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*Related PR: #6097*
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*Related Issue: #5988*

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