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Understanding why PM2 occasionally utilizes 100% of CPU and how to address it

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Posted Thu Mar 21 2024
Updated Thu Mar 21 2024

PM2, short for Process Manager 2, is a robust process manager for Node.js applications, designed to streamline the deployment and management of Node.js applications in production environments. Its versatility and ease of use make it a popular choice among developers and DevOps teams alike. However, like any software tool, PM2 may encounter issues that can impact system performance, such as occasional spikes in CPU usage.

Why Does PM2 Sometimes Use 100% of the Available CPU?

When PM2 utilizes 100% of the available CPU, it's often indicative of underlying issues within the Node.js applications it manages. One common scenario is that the applications being managed by PM2 may contain errors or bugs that force PM2 to continually restart them, resulting in increased CPU usage. Additionally, outdated versions of PM2 may also contribute to inefficiencies that lead to high CPU utilization.

Solutions to Address High CPU Usage by PM2:

1. Check for Errors in Node.js Applications:

The first step in addressing high CPU usage by PM2 is to inspect the Node.js applications it manages. Look for any errors, exceptions, or infinite loops within the application code that may cause instability and trigger frequent restarts by PM2. Thorough testing and debugging can help identify and resolve these issues.

2. Update PM2:

Ensure that you are using the latest version of PM2. Updates often include bug fixes, performance improvements, and optimizations that can help mitigate high CPU usage. You can update PM2 using the `pm2 update` command in your terminal. Regularly checking for updates and staying up-to-date with the latest releases is crucial for maintaining system stability and performance.

3. Monitor Application Performance:

Implement monitoring tools to track the performance of your Node.js applications managed by PM2. Monitoring metrics such as CPU usage, memory consumption, and request throughput can provide insights into application health and identify potential bottlenecks or performance issues early on. Tools like PM2's built-in monitoring feature or third-party monitoring solutions can be invaluable for proactive performance management. (eg htop)

4. Optimize Application Configuration:

Review and optimize the configuration settings of your Node.js applications to ensure optimal performance. Adjust parameters such as concurrency limits, resource allocation, and environment variables to match the specific requirements of your application workload and infrastructure. Fine-tuning these settings can help alleviate strain on system resources and reduce CPU usage.

5. Scale Resources Appropriately:

Evaluate the resource requirements of your Node.js applications and scale your infrastructure accordingly. Consider factors such as user traffic, workload intensity, and hardware capabilities when provisioning resources such as CPU cores, memory, and disk space. Scaling horizontally by distributing workload across multiple instances or vertically by upgrading hardware can help distribute the computational load and prevent CPU saturation.