child_process(子进程)


稳定性: 2 - 稳定

child_process 模块提供了以与 popen(3) 类似但不相同的方式衍生子进程的功能。 此功能主要由 child_process.spawn() 函数提供:

const { spawn } = require('child_process');
const ls = spawn('ls', ['-lh', '/usr']);

ls.stdout.on('data', (data) => {
  console.log(`stdout: ${data}`);
});

ls.stderr.on('data', (data) => {
  console.log(`stderr: ${data}`);
});

ls.on('close', (code) => {
  console.log(`子进程退出码:${code}`);
});

默认情况下, stdinstdoutstderr 的管道在父 Node.js 进程和衍生的子进程之间建立。 这些管道具有有限的(和平台特定的)容量。 如果子进程在没有捕获输出的情况下写入超出该限制的 stdout,则子进程将阻塞等待管道缓冲区接受更多的数据。 这与 shell 中的管道的行为相同。 如果不消费输出,则使用 { stdio: 'ignore' } 选项。

child_process.spawn() 方法异步地衍生子进程,且不阻塞 Node.js 事件循环。 child_process.spawnSync() 方法则以同步的方式提供等效功能,但会阻止事件循环直到衍生的进程退出或终止。

为方便起见, child_process 模块提供了 child_process.spawn()child_process.spawnSync() 的一些同步和异步的替代方法。 注意,这些替代方法中的每一个都是基于 child_process.spawn()child_process.spawnSync() 实现的。

对于某些用例,例如自动化的 shell 脚本,同步的方法可能更方便。 但是在大多数情况下,同步的方法会对性能产生重大影响,因为它会停止事件循环直到衍生的进程完成。

Stability: 2 - Stable

The child_process module provides the ability to spawn child processes in a manner that is similar, but not identical, to popen(3). This capability is primarily provided by the child_process.spawn() function:

const { spawn } = require('child_process');
const ls = spawn('ls', ['-lh', '/usr']);

ls.stdout.on('data', (data) => {
  console.log(`stdout: ${data}`);
});

ls.stderr.on('data', (data) => {
  console.log(`stderr: ${data}`);
});

ls.on('close', (code) => {
  console.log(`child process exited with code ${code}`);
});

By default, pipes for stdin, stdout, and stderr are established between the parent Node.js process and the spawned child. These pipes have limited (and platform-specific) capacity. If the child process writes to stdout in excess of that limit without the output being captured, the child process will block waiting for the pipe buffer to accept more data. This is identical to the behavior of pipes in the shell. Use the { stdio: 'ignore' } option if the output will not be consumed.

The child_process.spawn() method spawns the child process asynchronously, without blocking the Node.js event loop. The child_process.spawnSync() function provides equivalent functionality in a synchronous manner that blocks the event loop until the spawned process either exits or is terminated.

For convenience, the child_process module provides a handful of synchronous and asynchronous alternatives to child_process.spawn() and child_process.spawnSync(). Note that each of these alternatives are implemented on top of child_process.spawn() or child_process.spawnSync().

For certain use cases, such as automating shell scripts, the synchronous counterparts may be more convenient. In many cases, however, the synchronous methods can have significant impact on performance due to stalling the event loop while spawned processes complete.