How to create a child process using node.js (detailed tutorial)
When I read the chapter on multi-process before, I found that there are a lot of things about it. I also mentioned it when I was writing the Process module. I woke up from my lunch break this afternoon and calmed down to read it carefully and found that it is not too difficult to understand. So the following article mainly introduces you to the relevant information on how to create a child process using node.js. Friends in need can refer to it.
Preface
Node itself is a single process and uses driver mode to handle concurrency. In order to solve the waste of resources of a single process on a multi-core CPU, Node provides the cluster and child_process modules to create multiple child processes.
Node.js is single-threaded, which is a waste for machines that are now generally multi-processor. How can it be used? So the child_process module appeared. The child_process module can spawn, fork, and perform work on other processes.
The child_process module provides a new class ChildProcess, which can be used as a representation of accessing the child process from the parent process. The Process module is also a ChildProcess object. When you access process from the parent module, it is the parent ChildProcess object. When you access Process from the child process, it is the ChildProcess object
Understanding an object is nothing more than events, methods, and properties. The same goes for ChildProcess.
Each child process always has three stream objects: child.stdin, child.stdout, child.stderr. They may share the stdio stream of the parent process.
Here we first introduce how to operate the child process using the three methods of exec, spawn, and fork in the child_process module.
Create the node-childProcess file and create the node-childPro.js file in it.
One line of code is as follows:
console.log("进程 " + process.argv[2] + " 执行。" );
//换成下面的查看process.argv
//console.log("进程 " + process.argv + " 执行。" );exec() method
Create a new node- in the node-childProcess file childPro-exec.js file, the code is as follows:
const fs = require('fs');
const child_process = require('child_process');
for (var i = 0; i < 3; i++) {
//这里有空格请注意。分别代表node路径 node-childPro.js路径 i第几个进程。 node-childPro.js中的process.argv可以获取这些信息值
var childProcess = child_process.exec('node node-childPro.js '+i,
// 回调函数 子进程的输出以回调函数参数的形式返回
function (error, stdout, stderr) {
if (error) {
console.log(error.stack);
console.log('Error code: ' + error.code);
console.log('Signal received: ' + error.signal);
}
console.log('stdout: ' + stdout);
console.log('stderr: ' + stderr);
});
childProcess.on('exit', function (code) {
console.log('子进程已退出，退出码 ' + code);
});
}The terminal execution code result is as follows:
G:\node\node-childProcess> node node-childPro-exec.js 子进程已退出，退出码 0 stdout: 进程 0 执行。 stderr: 子进程已退出，退出码 0 stdout: 进程 1 执行。 stderr: 子进程已退出，退出码 0 stdout: 进程 2 执行。 stderr:
spawn() method
Create a new node-childPro-spawn.js in the node-childProcess file, with the code as follows:
const fs = require('fs');
const child_process = require('child_process');
for(var i=0; i<3; i++) {
var childProcess = child_process.spawn('node', ['node-childPro-spawn.js', i]);
childProcess.stdout.on('data', function (data) {
console.log('stdout: ' + data);
});
childProcess.stderr.on('data', function (data) {
console.log('stderr: ' + data);
});
childProcess.on('close', function (code) {
console.log('子进程已退出，退出码 '+code);
});
}The terminal execution code results are as follows:
G:\node\node-childProcess> node node-childPro-spawn.js stdout: 进程 0 执行。 子进程已退出，退出码 0 stdout: 进程 1 执行。 stdout: 进程 2 执行。 子进程已退出，退出码 0 子进程已退出，退出码 0
fork( )Method
Create a new node-childPro-fork.js in the node-childProcess file, with the code as follows:
const fs = require('fs');
const child_process = require('child_process');
for(var i=0; i<3; i++) {
var childProcess = child_process.fork("node-childPro.js", [i]);
childProcess.on('close', function (code) {
console.log('子进程已退出，退出码 ' + code);
});
}The terminal execution code results are as follows:
G:\node\node-childProcess> node node-childPro-fork.js 进程 0 执行。 进程 1 执行。 子进程已退出，退出码 0 进程 2 执行。 子进程已退出，退出码 0 子进程已退出，退出码 0
About exec, spawn, fork
## 1. The exec function is a friendly encapsulation of spawn. It adds Shell command parsing and can directly embed complex Command 2. The exec function caches the output of the sub-process and returns the output of the sub-process in the form of callback function parameters 3. After the child thread starts executing, spawn begins to continuously Data is returned from the child process to the main process (application scenario such as "system monitoring") 4.spawn does not support the callback function. It sends data to the main process through a stream, thereby realizing multi-process Data exchange between 5. fork() is a special case of spawn(), used to derive the Node process. In addition to all the methods of a normal ChildProcess instance, the returned object also has built-in communication channels. The above is what I compiled for everyone. I hope it will be helpful to everyone in the future. Related articles:How to implement component communication in vue-cli
Use angular to write the Message component
How to bind Json data source using EasyUI
The above is the detailed content of How to create a child process using node.js (detailed tutorial). For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
Is nodejs a backend framework?
Apr 21, 2024 am 05:09 AM
Node.js can be used as a backend framework as it offers features such as high performance, scalability, cross-platform support, rich ecosystem, and ease of development.
How to connect nodejs to mysql database
Apr 21, 2024 am 06:13 AM
To connect to a MySQL database, you need to follow these steps: Install the mysql2 driver. Use mysql2.createConnection() to create a connection object that contains the host address, port, username, password, and database name. Use connection.query() to perform queries. Finally use connection.end() to end the connection.
What are the global variables in nodejs
Apr 21, 2024 am 04:54 AM
The following global variables exist in Node.js: Global object: global Core module: process, console, require Runtime environment variables: __dirname, __filename, __line, __column Constants: undefined, null, NaN, Infinity, -Infinity
What is the difference between npm and npm.cmd files in the nodejs installation directory?
Apr 21, 2024 am 05:18 AM
There are two npm-related files in the Node.js installation directory: npm and npm.cmd. The differences are as follows: different extensions: npm is an executable file, and npm.cmd is a command window shortcut. Windows users: npm.cmd can be used from the command prompt, npm can only be run from the command line. Compatibility: npm.cmd is specific to Windows systems, npm is available cross-platform. Usage recommendations: Windows users use npm.cmd, other operating systems use npm.
Pi Node Teaching: What is a Pi Node? How to install and set up Pi Node?
Mar 05, 2025 pm 05:57 PM
Detailed explanation and installation guide for PiNetwork nodes This article will introduce the PiNetwork ecosystem in detail - Pi nodes, a key role in the PiNetwork ecosystem, and provide complete steps for installation and configuration. After the launch of the PiNetwork blockchain test network, Pi nodes have become an important part of many pioneers actively participating in the testing, preparing for the upcoming main network release. If you don’t know PiNetwork yet, please refer to what is Picoin? What is the price for listing? Pi usage, mining and security analysis. What is PiNetwork? The PiNetwork project started in 2019 and owns its exclusive cryptocurrency Pi Coin. The project aims to create a one that everyone can participate
Is there a big difference between nodejs and java?
Apr 21, 2024 am 06:12 AM
The main differences between Node.js and Java are design and features: Event-driven vs. thread-driven: Node.js is event-driven and Java is thread-driven. Single-threaded vs. multi-threaded: Node.js uses a single-threaded event loop, and Java uses a multi-threaded architecture. Runtime environment: Node.js runs on the V8 JavaScript engine, while Java runs on the JVM. Syntax: Node.js uses JavaScript syntax, while Java uses Java syntax. Purpose: Node.js is suitable for I/O-intensive tasks, while Java is suitable for large enterprise applications.
Is nodejs a back-end development language?
Apr 21, 2024 am 05:09 AM
Yes, Node.js is a backend development language. It is used for back-end development, including handling server-side business logic, managing database connections, and providing APIs.
Which one to choose between nodejs and java?
Apr 21, 2024 am 04:40 AM
Node.js and Java each have their pros and cons in web development, and the choice depends on project requirements. Node.js excels in real-time applications, rapid development, and microservices architecture, while Java excels in enterprise-grade support, performance, and security.
