What happens if you block the event loop in Node.js?
All other connections block, since Node.js runs JavaScript on a single thread. A blocking operation on the main thread stops all requests, which is the main performance concern in Node.js. Always prefer async APIs in production.
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More FAQs in Non-Blocking I/O in Node.js Explained: Why It Matters
A model where the thread initiates an I/O operation, moves on to other work, and processes the result when the operation completes via a callback. Node.js delegates I/O to libuv and processes callbacks through the event loop, so the single thread is not blocked waiting for I/O.
Because web servers handle many concurrent requests. If each request blocks the thread waiting for I/O, the server needs a thread per connection, using more memory. Non-blocking I/O handles thousands of connections on one thread efficiently.
By delegating I/O operations to libuv, which handles them asynchronously. When an operation completes, its callback is queued. The event loop processes these callbacks on the main thread, one at a time, without the thread being blocked.
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