NodeJS 真的是单线程的吗? [英] Is NodeJS really Single-Threaded?

问题描述

Node.js 解决了每个连接一个线程的问题"；通过将基于事件的模型置于其核心，使用事件循环而不是线程.所有昂贵的 I/O 操作总是异步执行，并在启动的操作完成时执行回调.

Node.js solves "One Thread per Connection Problem" by putting the event-based model at its core, using an event loop instead of threads. All the expensive I/O operations are always executed asynchronously with a callback that gets executed when the initiated operation completes.

Observation IF any Operation 发生时由epoll() 等多路复用机制处理.

The Observation IF any Operation occurs is handled by multiplexing mechanisms like epoll().

我现在的问题是:

• 为什么NodeJS在使用阻塞系统调用时不阻塞选择/epoll/kqueue?

• Why doesn't NodeJS block while using the blocking Systemcalls select/epoll/kqueue?

或者根本不是 NodeJS 单线程，所以第二个线程是
有必要用 select/epoll/kqueue 观察所有的 I/O 操作吗?

Or isn't NodeJS single threaded at all, so that a second Thread is
necessary to observe all the I/O-Operations with select/epoll/kqueue?

推荐答案

NodeJS is evented(来自 网站的第二行a>)，不是单线程的.它在内部处理执行 select/epoll/kqueue 处理所需的线程，而无需用户明确管理，但这并不意味着其中没有线程使用.

NodeJS is evented (2nd line from the website), not single-threaded. It internally handles threading needed to do select/epoll/kqueue handling without the user explicitly having to manage that, but that doesn't mean there is no thread usage within it.

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