VMs / EC2 High CPU Usage

Understanding Prometheus and Its Purpose

Prometheus is an open-source systems monitoring and alerting toolkit originally built at SoundCloud. It is designed to record real-time metrics in a time series database, built using a highly dimensional data model. Prometheus is widely used for monitoring applications and infrastructure, providing powerful querying capabilities and alerting features.

Symptom: High CPU Usage

The alert 'High CPU Usage' is triggered when the CPU usage on a VM or EC2 instance exceeds a predefined threshold. This is a common alert that helps in identifying performance bottlenecks and ensuring optimal resource utilization.

Details About the High CPU Usage Alert

When Prometheus detects that the CPU usage of a VM or EC2 instance surpasses the set threshold, it generates an alert. This threshold is often set based on the expected load and capacity of the instance. High CPU usage can lead to degraded performance and slow response times, affecting the overall user experience.

Why High CPU Usage Occurs

High CPU usage can occur due to several reasons, such as inefficient code, resource-intensive applications, or insufficient resources allocated to the instance. Identifying the root cause is crucial for resolving the issue effectively.

Steps to Fix the High CPU Usage Alert

Addressing high CPU usage involves a series of diagnostic and corrective actions. Below are the steps to resolve this alert:

Step 1: Identify CPU-Intensive Processes

Log into the affected VM or EC2 instance and use the following command to list processes by CPU usage:

top -o %CPU

This command will display a list of processes sorted by CPU usage, helping you identify which processes are consuming the most CPU resources.

Step 2: Optimize or Terminate Processes

Once you have identified the CPU-intensive processes, consider optimizing the code or logic of these processes. If certain processes are unnecessary, you may choose to terminate them using the kill command:

kill -9 <PID>

Replace <PID> with the process ID of the process you wish to terminate.

Step 3: Scale Resources

If the high CPU usage is due to insufficient resources, consider scaling your instance. For AWS EC2, you can change the instance type to one with more CPU capacity. Refer to the AWS EC2 Instance Resize Documentation for detailed instructions.

Step 4: Implement Auto-Scaling

To prevent future occurrences, consider implementing auto-scaling for your instances. Auto-scaling automatically adjusts the number of instances in response to load changes. Learn more about setting up auto-scaling in the AWS Auto Scaling Guide.

Conclusion

High CPU usage alerts are critical for maintaining the performance and reliability of your applications. By following the steps outlined above, you can effectively diagnose and resolve high CPU usage issues, ensuring your infrastructure runs smoothly.