工作线程

\Worker threads

源代码: lib/worker_threads.js

node:worker_threads 模块允许使用并行执行 JavaScript 的线程。要访问它:

\The node:worker_threads module enables the use of threads that execute JavaScript in parallel. To access it:

import worker_threads from 'node:worker_threads';'use strict';
const worker_threads = require('node:worker_threads');拷贝

工作线程对于执行 CPU 密集型的 JavaScript 操作很有用。它们对 I/O 密集型的工作帮助不大。Node.js 内置的异步 I/O 操作比工作线程更高效。

\Workers (threads) are useful for performing CPU-intensive JavaScript operations. They do not help much with I/O-intensive work. The Node.js built-in asynchronous I/O operations are more efficient than Workers can be.

与 child_process 或 cluster 不同,worker_threads 可以共享内存。它们通过传输 ArrayBuffer 实例或共享 SharedArrayBuffer 实例来实现。

\Unlike child_process or cluster, worker_threads can share memory. They do so by transferring ArrayBuffer instances or sharing SharedArrayBuffer instances.

import {
 Worker,
 isMainThread,
 parentPort,
 workerData,
} from 'node:worker_threads';
if (!isMainThread) {
 const { parse } = await import('some-js-parsing-library');
 const script = workerData;
 parentPort.postMessage(parse(script));
}
export default function parseJSAsync(script) {
 return new Promise((resolve, reject) => {
 const worker = new Worker(new URL(import.meta.url), {
 workerData: script,
 });
 worker.on('message', resolve);
 worker.on('error', reject);
 worker.on('exit', (code) => {
 if (code !== 0)
 reject(new Error(`Worker stopped with exit code ${code}`));
 });
 });
};'use strict';
const {
 Worker,
 isMainThread,
 parentPort,
 workerData,
} = require('node:worker_threads');
if (isMainThread) {
 module.exports = function parseJSAsync(script) {
 return new Promise((resolve, reject) => {
 const worker = new Worker(__filename, {
 workerData: script,
 });
 worker.on('message', resolve);
 worker.on('error', reject);
 worker.on('exit', (code) => {
 if (code !== 0)
 reject(new Error(`Worker stopped with exit code ${code}`));
 });
 });
 };
} else {
 const { parse } = require('some-js-parsing-library');
 const script = workerData;
 parentPort.postMessage(parse(script));
}拷贝

上面的示例为每个 parseJSAsync() 调用衍生工作线程。在实践中,为这些类型的任务使用工作线程池。否则,创建工作线程的开销可能会超过其收益。

\The above example spawns a Worker thread for each parseJSAsync() call. In practice, use a pool of Workers for these kinds of tasks. Otherwise, the overhead of creating Workers would likely exceed their benefit.

当实现工作线程池时,使用 AsyncResource API 通知诊断工具(例如提供异步的堆栈跟踪)有关任务与其结果之间的相关性。有关示例实现,请参阅 async_hooks 文档中的 "将 AsyncResource 用于 Worker 线程池"。

\When implementing a worker pool, use the AsyncResource API to inform diagnostic tools (e.g. to provide asynchronous stack traces) about the correlation between tasks and their outcomes. See "Using AsyncResource for a Worker thread pool" in the async_hooks documentation for an example implementation.

默认情况下,工作线程继承非进程特定的选项。参考 Worker constructor options 了解如何自定义工作线程选项,特别是 argv 和 execArgv 选项。

\Worker threads inherit non-process-specific options by default. Refer to Worker constructor options to know how to customize worker thread options, specifically argv and execArgv options.