The document provides an overview of Node.js architecture, highlighting its server-side nature, single-threaded model, and the use of the Chrome V8 runtime. It details components such as libuv for the event loop, asynchronous I/O, and C/C++ bindings which facilitate interaction between JavaScript and lower-level libraries. Additionally, it discusses async callback mechanisms and best practices to avoid blocking code, emphasizing the importance of managing CPU-bound tasks effectively.

1. Node.js Architecture
Overview

2. Introduction to Node
• Server Side.
• Single Threaded.
• Build on Chrome V8 Runtime Environment.
• Uses an event driven, non blocking I/O Model.

3. Architecture

4. V8
• JIT
• Written in C++
• Compiles JS directly into assembly code.
• Call Stack, Heap.
• Garbage Collector
• New space
• Old space.

5. Libuv
• Event Loop.
• Asynchronous I/O.
• Thread pool.
• Networking.
• Asynchronous TCP & UDP sockets.
• File system read/write.

6. Other C/C++ Components.
• Provide important functionality
• Compressing
• Encryption
• Asynchronous DNS requests
• Etc.

7. Application/Node.js API
• Application Code.
• Modules.

8. Node.js Bindings
• Glue code
• Code in different languages can interact with each other.
• Expose core C++ libraries to JS.
• Motivation
• Reusability
• Performance

9. C/C++ Addons
• Own Glue Code to include third party or own C/C++ library.
Think of Addons and Bindings as bridges between Node.js C/C++
and Your JS Code.

10. • Code compiled by V8.
• Communicate with low level node.js components.
• All events registered with node.js.
• Event triggered enqueued in event queue.
• Event loop dequeue events in the queue and putting them onto
the call stack.

11. How async callback works
Call Stack Node Core Libraries
(Libuv)
Event Loop
Event Queue

12. • Call Stack is JS Runtime (Single threaded).
• Executes the tasks.
• C++ libraries like Libuv make async programming possible in Node.
• Event Loop (Also part of libuv)
• Loops around JS Runtime.
• If JS runtime is free it pulls tasks from event queue to call stack so that JS
Runtime can execute them.

13. • I/O operation on call stack.
• Delegates tasks to libuv for processing.
• Libuv maintains thread pool for I/O operations And DNS related.
• Thread interact with Node’s low-level libraries.
• Enqueue event back to event queue.
• Libuv user multiple strategies to achieve asynchronicity depends upon
nature of function.

14. • Be aware of blocking code.
• Avoid long running functions that require long computations.
• Use ES6 generators in that kind of functions that will make code async. By
explicitly pause them and signal them to resume.
• Delegate CPU bound tasks to child processes.
• explicit multi-processing/multi-threading
• Clusters.
• Webworker-threads.

15. The End
• Thanks for listening
• Questions would be appreciated.