npm cache clean 후 설치 속도 개선

Introduction

Slow npm install times can waste hours of development time. After cleaning the cache, installations sometimes become even slower because packages must be re-downloaded. This post covers how to properly manage npm cache for optimal installation speed.

Environment

node --version
# v20.11.0

npm --version
# 10.2.4

# Check current cache size
npm cache ls 2>/dev/null | wc -l
# Or on Windows:
dir /s %LOCALAPPDATA%\npm-cache 2>nul | find "File(s)"

Problem

After running npm cache clean --force, installation became extremely slow:

npm cache clean --force
# npm warn using --force Recommended protections deprecated.

npm install
# Takes 10+ minutes to complete
# Previously took 30 seconds

The cache was cleared, so npm had to download every package from scratch.

Analysis

The npm cache stores:

%LOCALAPPDATA%\npm-cache\_cacache\    ← Package tarballs
%LOCALAPPDATA%\npm-cache\_logs\       ← Install logs
%LOCALAPPDATA%\npm-cache\_npx\        ← npx cache

When the cache is empty, npm must:

1. Resolve all dependencies from the registry
2. Download all tarballs
3. Extract and install them

This is much slower than using cached packages.

Solution

Step 1: Check current cache status

npm cache verify
# Cache verified and content verified

Step 2: Use npm ci for CI/CD (not npm install)

# In CI/CD, always use ci
npm ci

# npm ci does:
# 1. Deletes node_modules
# 2. Installs exactly from package-lock.json
# 3. Uses cache when available
# 4. Is faster and more reliable

Step 3: Configure cache location

# Set custom cache directory
npm config set cache /path/to/fast/ssd/npm-cache

# Check current cache location
npm config get cache
# C:\Users\user\AppData\Local\npm-cache

Step 4: Use a local mirror

# Use Verdaccio as local registry
npm install -g verdaccio
verdaccio &

# Configure npm to use local registry
npm set registry http://localhost:4873/

# Or use a specific registry for your organization
npm config set @mycompany:registry https://npm.mycompany.com/

Step 5: Parallel downloads

# Increase network concurrency
npm config set maxsockets 15

# Use different registry for faster access
npm config set registry https://registry.npmmirror.com/

Step 6: Optimize package-lock.json

// package.json - use exact versions for faster resolution
{
  "dependencies": {
    "express": "4.18.2",        // Exact version - fast
    "lodash": "^4.17.21",      // Range - needs resolution
    "react": "18.2.0"          // Exact version - fast
  }
}

Step 7: Cache management script

#!/bin/bash
# optimize-npm.sh

echo "Verifying npm cache..."
npm cache verify

echo "Cleaning old logs..."
rm -rf $(npm config get cache)/_logs/*

echo "Checking cache size..."
du -sh $(npm config get cache)

echo "Installing dependencies..."
npm ci --prefer-offline --no-audit --no-fund

echo "Done!"

# Windows version
Write-Host "Verifying npm cache..."
npm cache verify

Write-Host "Cleaning old logs..."
Remove-Item -Path "$(npm config get cache)\_logs\*" -Force -ErrorAction SilentlyContinue

Write-Host "Installing dependencies..."
npm ci --prefer-offline --no-audit --no-fund

Write-Host "Done!"

Lessons Learned

1. Never use npm cache clean --force in CI/CD - Use npm ci instead
2. Use --prefer-offline to prioritize cached packages
3. Set up a local registry for teams with slow internet connections
4. Use exact versions in package.json when possible
5. Monitor cache size - Clean old packages periodically with npm cache verify

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