PM2 vs NPM: Why PM2 is a Game-Changer for Node.js App Management

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Introduction

Managing Node.js applications in production requires more than just npm start. While NPM scripts are great for development, they don’t offer built-in crash recovery, process monitoring, or scaling options. That’s why developers turn to PM2 — a robust, feature-rich process manager for Node.js.

What is PM2?

PM2 is a production-grade process manager for Node.js that keeps your app running, even if it crashes. It supports features like automatic restarts, load balancing across CPU cores, and built-in log management. It's ideal for long-running apps and production environments where reliability is critical.

What are NPM Scripts Good For?

NPM scripts like npm start or npm run dev are commonly used in local development. They're great for running build tools, testing environments, or quick local servers. But in production, they fall short when it comes to fault tolerance and uptime.

Why PM2 is Better for Node.js App Management

PM2 Advantages Over NPM

• Auto-Restart: PM2 automatically restarts your app when it crashes.
• Cluster Mode: Take advantage of all CPU cores.
• Monitoring: Use pm2 monit for real-time stats.
• Startup Scripts: PM2 can configure your app to launch on reboot.
• Log Handling: Keeps logs organized and rotates them automatically.

Getting Started with PM2 (Step-by-Step)

1. Install PM2

npm install -g pm2

2. Start Your App with PM2

pm2 start app.js --name "my-app"

3. Monitor the App

pm2 monit

4. Enable Auto-Startup on Server Reboot

pm2 startup
pm2 save

pm2 startup pm2 save

• Start a process:

pm2 start app.js --name "my-app"

• Stop a process:

pm2 stop my-app

• Restart a process:

pm2 restart my-app

• Reload a process (zero downtime):

pm2 reload my-app

• List all running processes:

pm2 list

• Show logs for all apps:

pm2 logs

• Show logs with specific lines:

pm2 logs --lines 100

• Delete a process:

pm2 delete my-app

• Monitor all processes in real time:

pm2 monit

• Generate system startup script (for auto-run):

pm2 startup

• Save current PM2 process list:

pm2 save

• Describe a specific app:

pm2 describe my-app

• Flush logs:

pm2 flush

• Install and configure log rotation:

pm2 install pm2-logrotate

What is pm2-logrotate?

pm2-logrotate is a PM2 module that automatically rotates and manages logs generated by your applications managed with PM2.

• Prevent disk space issues from large log files
• Automatically archive, compress, or delete old logs
• Keep logs organized and manageable

Why Use It?

PM2 generates two types of logs for each process:

• out.log – Standard output (e.g., console.log)
• error.log – Standard error (e.g., console.error)

Without log rotation, these files can grow endlessly.

PM2 Cluster Mode: Scale Like a Pro

pm2 start "node index.js" -i 5

This sets the number of instances to 5, using cluster mode.

• Uses Node.js Cluster API
• Runs multiple instances across CPU cores
• Automatically balances load across these instances
• Useful for scaling on multi-core systems

So this means: "Start 5 clustered instances of node index.js, managed by PM2."

When Should You Still Use NPM?

NPM is still useful in development, or for simple scripts and tools that don’t require long-term reliability. It’s fast and built-in, but it’s not meant to handle production concerns like log management, crashes, or server reboots.

Common Mistakes Developers Make with PM2

• ❌ Not running pm2 save — causes loss on reboot
• ❌ Skipping pm2 startup — app won’t auto-run after restart
• ❌ Ignoring log rotation — logs can fill the disk
• ❌ Using PM2 in dev only — its true power is in production

Conclusion: PM2 vs NPM

PM2 is a must-have for anyone running Node.js applications in production. It gives you control, reliability, and monitoring with just a few commands. While NPM is great for dev tasks, PM2 takes things to the next level when uptime and performance matter most.