Process manager - PM2

Perfect — let’s go through PM2, a widely used process manager for Node.js that’s essential for production deployments.

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1️⃣ What is PM2?

• PM2 = Production Process Manager for Node.js

• Helps keep applications alive, restart on failure, and monitor performance

• Works for single apps, clusters, or multiple apps

Key Features:

1. Process management: Start, stop, restart Node apps

2. Clustering: Run app across all CPU cores

3. Monitoring: Track CPU, memory, uptime

4. Log management: Aggregate and persist logs

5. Auto-restart: Restart apps if they crash or the server restarts

6. Zero-downtime reloads: Graceful reloads for updates

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2️⃣ Installing PM2

npm install pm2 -g

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3️⃣ Starting and Managing Apps

Start a Node App

pm2 start app.js --name my-app

• --name → assign a friendly process name

List Running Processes

pm2 list

Stop / Restart App

pm2 stop my-app
pm2 restart my-app
pm2 reload my-app   # zero-downtime reload

Delete App

pm2 delete my-app

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4️⃣ Clustering Mode

• Utilize all CPU cores for better throughput

pm2 start app.js -i max   # max = number of CPU cores

• PM2 automatically spawns multiple worker processes

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5️⃣ Monitoring & Logs

Real-time Monitoring

pm2 monit

Logs

pm2 logs my-app       # live logs
pm2 flush             # clear logs
pm2 logs --lines 100  # last 100 lines

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6️⃣ Auto Startup on Server Reboot

pm2 startup
pm2 save

• Ensures Node apps restart automatically after server reboot

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7️⃣ Ecosystem File (Optional)

• Manage multiple apps with a JSON/YAML configuration file

// ecosystem.config.js
module.exports = {
  apps: [
    {
      name: "my-app",
      script: "./app.js",
      instances: "max",
      exec_mode: "cluster",
      watch: true
    }
  ]
};

• Start all apps: pm2 start ecosystem.config.js

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8️⃣ Key Takeaways

1. PM2 is essential for production Node.js apps

2. Provides process management, clustering, monitoring, and logging

3. Supports zero-downtime reloads for seamless deployments

4. Easily integrates with server startup scripts

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Next, we could cover Node.js production best practices, combining performance, monitoring, logging, security, clustering, and deployment strategies for real-world applications.

Do you want me to go there next?