Non-blocking I/O in Node.js means the program does not wait for slow operations like file reads, database calls, or network requests; instead, it sends these tasks to the system or thread pool and continues executing other code, using the event loop to push results back as callbacks, promises, or async responses when operations complete, which enables handling thousands of concurrent requests without creating thousands of threads.
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What does non-blocking I/O actually mean in real-world systems?Added:
What exactly is non-blocking IO in practical terms? So non-blocking IO means the program doesn't wait for the slow operations like file reads, database calls or network request.
Instead of waiting, NodeJS sends the task to the system or thread pull and continues executing other code. When the operation finishes, NodeJS uses the event loop to push the result back as a call back, promise or async response. So this allows NodeJS to handle thousands of concurrent requests without creating thousands of threads. So in practical terms, no non-blocking IO means Node.js keeps working while IIO happens in the background.
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