Node.js

Is Node.js Open Source?

Yes, Node.js is open source. It is governed by the OpenJS Foundation and released under the MIT License, allowing developers to freely use, modify, and distribute the software. Its open-source nature has contributed to a large ecosystem of community-driven modules and tools via npm (Node Package Manager).

Node.js Architecture – An Overview

How Does Node.js Handle Concurrency?

Node.js uses a single-threaded event loop with non-blocking I/O—allowing many simultaneous connections efficiently, as long-running tasks are offloaded to background threads via libuv.

What is npm?

npm (Node Package Manager) is the default registry and CLI for managing packages and dependencies in Node.js projects.

What is the Event Loop?

The event loop processes callbacks in phases—polling I/O, executing timers, handling immediate tasks—enabling the asynchronous, non-blocking nature of Node.js

When working with Node.js it is essential to proactively monitor the behavior of the event loop – key metrics to monitor that are associated with the event loop are shown in this screenshot from the eG Enterprise monitoring platform

What are the Advantages of Using Node.js?

Benefits and Advantages of Node.js include:

• High Performance & Scalability: Node.js is designed for speed and can efficiently manage many simultaneous connections thanks to its event-driven, non-blocking architecture, making it ideal for real-time applications and APIs. However, to ensure this promised performance is consistently delivered and that the application scales smoothly under real-world pressure, having deep visibility into its live behavior through monitoring is crucial.
• Unified Full-Stack Development: Using JavaScript on both the client and server streamlines the development process, simplifies team structure, and enables seamless code sharing. This unified approach makes it easier to trace issues across the entire stack but requires end-to-end visibility to quickly pinpoint whether a bottleneck originates in the front-end, back-end, or in the communication between them.
• Vast Ecosystem via npm: The Node Package Manager (npm) provides access to the world's largest software registry. While this vast collection of open-source libraries can dramatically accelerate development, it also introduces external dependencies. It becomes critical to monitor how these third-party packages impact overall application performance, security, and stability.

What are the Limitations of Node.js?

Limitations of Node.js that should be taken into consideration include:

• CPU-Intensive Tasks: Node.js uses one main thread to handle tasks. If a task requires a lot of processing power, like complex calculations, it can block this thread and make your entire application unresponsive. Monitoring CPU usage is crucial to identify these performance bottlenecks before they impact users.
• Asynchronous Programming Complexity: Writing code that handles many operations at once can be difficult to get right. Even though modern tools make it easier, mistakes in this asynchronous logic can lead to subtle bugs or memory leaks. Application performance monitoring helps track down these hard-to-find issues that arise from complex code paths.
• Single-Threaded Limitations: Because Node.js relies on a single main thread, one unhandled error is enough to bring down the entire application. This makes continuous monitoring for errors and application uptime essential to ensure your service remains available and reliable.

Given these potential challenges, proactive monitoring is not just a best practice but a critical component for maintaining a reliable and performant Node.js application.

Where Can I Find Details of Node.js Releases?

Information on Node.js releases is available here: Node.js — Node.js Releases.

Can I Get a Commercially Supported Version of Node.js?

Commercial support for versions past the Maintenance phase is available through the OpenJS Ecosystem Sustainability Program partner HeroDevs.

How Should I Monitor Node.js Applications?

When monitoring Node.js applications you should track and monitor the health of the server or container running Node.js. Metrics pertaining to resource usage should be used and you will also want to monitor the underlying infrastructure supporting the server or container – whether that be physical hardware or cloud / virtualized infrastructure. Basic metrics you should monitor include:

• CPU usage – Node.js apps are CPU-sensitive.
• Memory usage – Watch for leaks or increasing trends.
• Disk I/O & network I/O – Especially if your app is doing heavy file or network operations.

Application-level monitoring should capture metrics specific to Node.js, such as:

• Event Loop Lag – Detect if the event loop is blocked.
• Heap & Garbage Collection – Monitor memory allocation and GC pauses.
• Request Latency & Throughput – Measure response times and requests per second.
• Error Rates –Track HTTP 4xx/5xx responses and exceptions.

APM tools that capture application-level metrics include Dynatrace, Datadog, eG Enterprise and New Relic.

Monitoring should also cover the V8 engine.

What eG Enterprise Offers for Advanced Monitoring of Node.js

• Measures Node.js application code performance with application-level transaction details including per URL drilldowns and transaction details for each and every access to web and e-Commerce sites.
• Automatic inspection and continual monitoring of database queries and database performance. Use the Slow SQL Queries feature to identify queries that are taking excessive or abnormal time to execute. All major database technologies including MongoDB, MySQL, PostgreSQL and more supported.


Coss-application transaction flow analysis will pinpoint issues such as slow database queries, application server issues or slow / failing remote calls

• Distributed Transaction Flow analysis leverages a tag-and-follow technique to trace transactions across multiple tiers – Node.js and other (Java, PHP, .NET) APM tiers.
• Additional contextual information capture. For example, when monitoring an e-Commerce website, details of what products are viewed and what are the most searched products, etc. are captured.
• Code level exceptions are tracked and captured including comprehensive exception details.
• Comprehensive live and historical out-of-the-box Node.js reports cover all aspects of business transactions in an application including: Health Trend, Load Response vs Time Analysis, Unique User / Session and more.

To learn more about eG Enterprise support for Node.js applications, see Node.js Application Performance Monitoring.