1. Client Request Handling
A client (user) initiates a request to the server.
The server runs on Node.js, but it could also be based on PHP, Golang, etc.
Node.js architecture starts processing the request upon arrival.
2. Event Queue (Event Queue Mechanism)
All incoming requests are first placed in the Event Queue.
Multiple requests are queued sequentially in the First In, First Out (FIFO) manner.
3. Event Loop Mechanism
The Event Loop continuously monitors the Event Queue for pending requests.
It picks up requests one by one and determines whether they require blocking or non-blocking operations.
4. Non-Blocking (Asynchronous) Operations
If a request is non-blocking, Node.js processes it immediately.
Once processed, the response is sent back to the client.
Example: Simple calculations, retrieving data from in-memory storage, etc.
5. Blocking (Synchronous) Operations & Thread Pool
If a request is blocking, it is sent to the Thread Pool for processing.
The Thread Pool consists of worker threads that handle CPU-intensive or I/O operations.
A worker thread processes the task and returns the result.
Once completed, Node.js sends the response back to the client.
Example: Reading files, database queries, cryptographic processing, etc.
6. Key Concepts in Node.js Execution
Event-Driven Architecture: Node.js operates on an event-based model for handling multiple requests efficiently.
Single-Threaded with Worker Threads: Although Node.js is single-threaded, it offloads heavy tasks to a pool of worker threads.
Asynchronous Execution: Tasks are handled asynchronously whenever possible to avoid blocking the main execution thread.