Troubleshooting an EC2 instance that reaches 💯% CPU utilization 🔥

Troubleshooting an EC2 instance that reaches 100% CPU utilization involves several steps to identify the root cause and mitigate the issue. Here’s a breakdown of the process:

1. Monitor and Identify the Issue:

• CloudWatch Metrics: Check the CPU utilization metrics in Amazon CloudWatch to confirm the instance is reaching 100% CPU.

• Logs: Review system and application logs (e.g., /var/log/messages, /var/log/syslog) to identify any patterns or anomalies.

• Processes: Use tools like top, htop, or ps to identify which processes are consuming the most CPU.

2. Immediate Actions:

• Restart Services: If a particular service is causing high CPU, consider restarting it. For example, if a web server is causing the issue, you can restart it using commands like sudo systemctl restart apache2 or sudo systemctl restart nginx.

• Kill Processes: If a specific process is stuck or causing high CPU usage, you can terminate it using the kill command.

3. Analyze the Cause:

• High Traffic: Check if there is an unusual spike in traffic causing high CPU usage. This can be done by analyzing web server logs or monitoring network traffic.

• Code Issues: Look for any inefficient code, infinite loops, or resource-intensive operations in your applications.

• Background Jobs: Identify if there are any scheduled tasks, cron jobs, or background processes that are consuming resources.

• Security: Ensure the instance is not compromised. High CPU usage can be a sign of malicious activities, such as cryptocurrency mining.

4. Mitigation Strategies:

• Scaling:

  • Vertical Scaling: Increase the instance size (e.g., upgrade from a t2.micro to a t3.medium).

  • Horizontal Scaling: Add more instances and distribute the load using an Elastic Load Balancer (ELB).

• Optimization:

  • Code Optimization: Refactor the code to be more efficient.

  • Database Optimization: Ensure database queries are optimized and use indexes properly.

  • Caching: Implement caching mechanisms to reduce the load on the instance (e.g., using Redis or Memcached).

5. Long-term Solutions:

• Auto Scaling: Configure Auto Scaling groups to automatically add or remove instances based on CPU utilization thresholds.

• Load Balancing: Use an Application Load Balancer (ALB) to distribute incoming traffic across multiple instances.

• Performance Monitoring: Continuously monitor the performance using CloudWatch, setting up alarms for CPU thresholds.

6. Documentation and Review:

• Documentation: Document the issue, steps taken, and the resolution for future reference.

• Review: Regularly review the system’s performance and make adjustments as necessary to prevent future occurrences.

Example Commands:

• Monitor Processes:

    top
    htop
    ps aux --sort=-%cpu
  

• Restart a Service:

    sudo systemctl restart <service-name>
  

• Kill a Process:

    sudo kill -9 <pid>
  

By systematically following these steps, you can effectively troubleshoot and resolve high CPU utilization issues on your EC2 instance.