From Node docs & community we know:
Node.js uses a small number of threads to handle many clients. In Node.js there are two types of threads: one Event Loop (aka the main loop, main thread, event thread, etc.), and a pool of k Workers in a Worker Pool (aka the threadpool).
If a thread is taking a long time to execute a callback (Event Loop) or a task (Worker), then the thread is blocked and may not respond to futher requests.
- You should make sure you never block the Event Loop.
- Also JavaScript callbacks should complete quickly
A common use case in production application that one might have is consuming messages from a queue (for instance: aws SQS). This project contains results and implementation of bad and good consumer for that use case.
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Run implementation of http server and queue consumer on main event loop
npm run start:bad-consumer -
The result is the event loop will end up blocked and refusing connections or timing out:
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Run implementation of http server with queue consumer a child process
npm run start:good-consumer -
The result is you dont block the main event loop with consumer processing:
