search
HomeWeb Front-endJS TutorialAnalyzing the use of Node.js cluster module in detail

This time I will bring you an analysisNode.js Detailed explanation of the use of cluster module, detailed explanation of the use of Node.js cluster moduleWhat are the precautions, the following is a practical case, let's take a look take a look.

cluster module overview

The node instance is a single-threaded job. In server-side programming, multiple node instances are usually created to handle client requests to improve system throughput. For such multiple node instances, we call it a cluster.

With the help of node's cluster module, developers can obtain the benefits of cluster services without modifying the original project code with almost no modifications.

The cluster has the following two common implementation solutions, and the cluster module that comes with node adopts the second solution.

Option 1: Multiple node instances and multiple ports

The node instances in the cluster each listen to different ports, and then the reverse proxy implements the request to multiple Distribution of ports.

  1. Advantages: Simple implementation, each instance is relatively independent, which is good for service stability.

  2. Disadvantages: increased port occupancy, communication between processes is more troublesome.

Option 2: The main process forwards the request to the child process

In the cluster, create a main process (master) and several child processes ( worker). The master monitors client connection requests and forwards them to workers according to specific policies.

  1. Advantages: Usually only one port is occupied, communication is relatively simple, and the forwarding strategy is more flexible.

  2. Disadvantages: The implementation is relatively complex and requires high stability of the main process.

Getting started example

In the cluster module, the main process is called master and the child process is called worker.

The example is as follows, create server instances with the same number of CPUs to handle client requests. Note that they are all listening on the same port.

// server.js
var cluster = require('cluster');
var cpuNums = require('os').cpus().length;
var http = require('http');
if(cluster.isMaster){
 for(var i = 0; i <p style="text-align: left;">Create batch script: ./req.sh. </p><pre class="brush:php;toolbar:false">#!/bin/bash
# req.sh
for((i=1;i<p style="text-align: left;">The output is as follows. As you can see, the responses come from different processes. </p><blockquote style="text-align: left;"><p style="text-align: left;">response from worker 23735<br>response from worker 23731<br>response from worker 23729<br>response from worker 23730</p></blockquote><p style="text-align: left;"><span style="color: #ff0000"><strong>cluster Module implementation principle</strong></span></p><p style="text-align: left;">To understand the cluster module, we mainly need to understand three questions:</p><ol class=" list-paddingleft-2">
<li><p style="text-align: left;">How do master and workers communicate? </p></li>
<li><p style="text-align: left;">How to achieve port sharing for multiple server instances? </p></li>
<li><p style="text-align: left;">With multiple server instances, how do requests from clients be distributed to multiple workers? </p></li>
</ol><p style="text-align: left;">The following will be introduced based on the schematic diagram. For source code level introduction, you can refer to the author's github. </p><p style="text-align: left;"><strong>Question 1: How to communicate between master and worker</strong></p><p style="text-align: left;">This question is relatively simple. The master process creates worker processes through cluster.fork(). Cluster.fork() internally creates child processes through child_process.fork(). </p><p style="text-align: left;">In other words: </p><ol class=" list-paddingleft-2">
<li><p style="text-align: left;">The master process and the worker process are the relationship between parent and child processes. </p></li>
<li><p style="text-align: left;">The master process and the worker process can communicate through the IPC channel. (Important) </p></li>
</ol><p style="text-align: left;"><strong>Question 2: How to implement port sharing</strong></p><p style="text-align: left;">In the previous example, servers created in multiple wokers listened to the same port. port 3000. Generally speaking, if multiple processes listen to the same port, the system will report an error. </p><p style="text-align: left;">Why is our example okay? </p><p style="text-align: left;">The secret is that in the net module, the listen() method is specially processed. Depending on whether the current process is a master process or a worker process: </p><ol class=" list-paddingleft-2">
<li><p style="text-align: left;">master process: listen to requests normally on this port. (No special treatment)</p></li>
<li><p style="text-align: left;">worker进程:创建server实例。然后通过IPC通道,向master进程<a href="http://www.php.cn/php/php-send-message.html" target="_blank">发送消息</a>,让master进程也创建 server 实例,并在该端口上监听请求。当请求进来时,master进程将请求转发给worker进程的server实例。</p></li>
</ol><p style="text-align: left;">归纳起来,就是:master进程监听特定端口,并将客户请求转发给worker进程。</p><p style="text-align: left;">如下图所示:</p><p style="text-align: left;"><img src="/static/imghwm/default1.png" data-src="https://img.php.cn/upload/article/000/061/021/392d7540fb965981c01f575d74dd8f15-0.png?x-oss-process=image/resize,p_40" class="lazy" alt=""    style="max-width:90%"  style="max-width:90%"></p><p style="text-align: left;"><strong>问题3:如何将请求分发到多个worker</strong></p><p style="text-align: left;">每当worker进程创建server实例来监听请求,都会通过IPC通道,在master上进行注册。当客户端请求到达,master会负责将请求转发给对应的worker。</p><p style="text-align: left;">具体转发给哪个worker?这是由转发策略决定的。可以通过环境变量NODE_CLUSTER_SCHED_POLICY设置,也可以在cluster.setupMaster(options)时传入。</p><p style="text-align: left;">默认的转发策略是轮询(SCHED_RR)。</p><p style="text-align: left;">当有客户请求到达,master会轮询一遍worker列表,找到第一个空闲的worker,然后将该请求转发给该worker。</p><p style="text-align: left;"><strong>master、worker内部通信小技巧</strong></p><p style="text-align: left;">在开发过程中,我们会通过 process.on('message', fn) 来实现进程间通信。</p><p style="text-align: left;">前面提到,master进程、worker进程在server实例的创建过程中,也是通过IPC通道进行通信的。那会不会对我们的开发造成干扰呢?比如,收到一堆其实并不需要关心的消息?</p><p style="text-align: left;">答案肯定是不会?那么是怎么做到的呢?</p><p style="text-align: left;">当发送的消息包含cmd字段,且改字段以NODE_作为前缀,则该消息会被视为内部保留的消息,不会通过message<a href="http://www.php.cn/php/php-tp-incident.html" target="_blank">事件</a>抛出,但可以通过监听'internalMessage'捕获。</p><p style="text-align: left;">以worker进程通知master进程创建server实例为例子。worker伪代码如下:</p><pre class="brush:php;toolbar:false">// woker进程
const message = {
 cmd: 'NODE_CLUSTER',
 act: 'queryServer'
};
process.send(message);

master伪代码如下:

worker.process.on('internalMessage', fn);

相信看了本文案例你已经掌握了方法,更多精彩请关注php中文网其它相关文章!

推荐阅读:

设计模式的策略模式怎样在前端中使用

如何对微信小程序进行开发

The above is the detailed content of Analyzing the use of Node.js cluster module in detail. For more information, please follow other related articles on the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Behind the Scenes: What Language Powers JavaScript?Behind the Scenes: What Language Powers JavaScript?Apr 28, 2025 am 12:01 AM

JavaScript runs in browsers and Node.js environments and relies on the JavaScript engine to parse and execute code. 1) Generate abstract syntax tree (AST) in the parsing stage; 2) convert AST into bytecode or machine code in the compilation stage; 3) execute the compiled code in the execution stage.

The Future of Python and JavaScript: Trends and PredictionsThe Future of Python and JavaScript: Trends and PredictionsApr 27, 2025 am 12:21 AM

The future trends of Python and JavaScript include: 1. Python will consolidate its position in the fields of scientific computing and AI, 2. JavaScript will promote the development of web technology, 3. Cross-platform development will become a hot topic, and 4. Performance optimization will be the focus. Both will continue to expand application scenarios in their respective fields and make more breakthroughs in performance.

Python vs. JavaScript: Development Environments and ToolsPython vs. JavaScript: Development Environments and ToolsApr 26, 2025 am 12:09 AM

Both Python and JavaScript's choices in development environments are important. 1) Python's development environment includes PyCharm, JupyterNotebook and Anaconda, which are suitable for data science and rapid prototyping. 2) The development environment of JavaScript includes Node.js, VSCode and Webpack, which are suitable for front-end and back-end development. Choosing the right tools according to project needs can improve development efficiency and project success rate.

Is JavaScript Written in C? Examining the EvidenceIs JavaScript Written in C? Examining the EvidenceApr 25, 2025 am 12:15 AM

Yes, the engine core of JavaScript is written in C. 1) The C language provides efficient performance and underlying control, which is suitable for the development of JavaScript engine. 2) Taking the V8 engine as an example, its core is written in C, combining the efficiency and object-oriented characteristics of C. 3) The working principle of the JavaScript engine includes parsing, compiling and execution, and the C language plays a key role in these processes.

JavaScript's Role: Making the Web Interactive and DynamicJavaScript's Role: Making the Web Interactive and DynamicApr 24, 2025 am 12:12 AM

JavaScript is at the heart of modern websites because it enhances the interactivity and dynamicity of web pages. 1) It allows to change content without refreshing the page, 2) manipulate web pages through DOMAPI, 3) support complex interactive effects such as animation and drag-and-drop, 4) optimize performance and best practices to improve user experience.

C   and JavaScript: The Connection ExplainedC and JavaScript: The Connection ExplainedApr 23, 2025 am 12:07 AM

C and JavaScript achieve interoperability through WebAssembly. 1) C code is compiled into WebAssembly module and introduced into JavaScript environment to enhance computing power. 2) In game development, C handles physics engines and graphics rendering, and JavaScript is responsible for game logic and user interface.

From Websites to Apps: The Diverse Applications of JavaScriptFrom Websites to Apps: The Diverse Applications of JavaScriptApr 22, 2025 am 12:02 AM

JavaScript is widely used in websites, mobile applications, desktop applications and server-side programming. 1) In website development, JavaScript operates DOM together with HTML and CSS to achieve dynamic effects and supports frameworks such as jQuery and React. 2) Through ReactNative and Ionic, JavaScript is used to develop cross-platform mobile applications. 3) The Electron framework enables JavaScript to build desktop applications. 4) Node.js allows JavaScript to run on the server side and supports high concurrent requests.

Python vs. JavaScript: Use Cases and Applications ComparedPython vs. JavaScript: Use Cases and Applications ComparedApr 21, 2025 am 12:01 AM

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

WebStorm Mac version

WebStorm Mac version

Useful JavaScript development tools

MantisBT

MantisBT

Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

ZendStudio 13.5.1 Mac

ZendStudio 13.5.1 Mac

Powerful PHP integrated development environment

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

PhpStorm Mac version

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool