mirror of https://github.com/nodejs/node.git
worker: add ESM version examples to worker docs
PR-URL: https://github.com/nodejs/node/pull/57645 Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
This commit is contained in:
fisker Cheung
GitHub
parent
609df89cd3
commit
0699a99bbe
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@ -9,7 +9,13 @@
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The `node:worker_threads` module enables the use of threads that execute
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JavaScript in parallel. To access it:
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```js
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```mjs
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import worker from 'node:worker_threads';
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```
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```cjs
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'use strict';
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const worker = require('node:worker_threads');
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```
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@ -21,9 +27,43 @@ Unlike `child_process` or `cluster`, `worker_threads` can share memory. They do
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so by transferring `ArrayBuffer` instances or sharing `SharedArrayBuffer`
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instances.
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```js
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```mjs
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import {
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Worker,
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isMainThread,
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parentPort,
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workerData,
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} from 'node:worker_threads';
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if (!isMainThread) {
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const { parse } = await import('some-js-parsing-library');
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const script = workerData;
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parentPort.postMessage(parse(script));
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}
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export default function parseJSAsync(script) {
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return new Promise((resolve, reject) => {
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const worker = new Worker(new URL(import.meta.url), {
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workerData: script,
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});
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worker.on('message', resolve);
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worker.on('error', reject);
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worker.on('exit', (code) => {
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if (code !== 0)
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reject(new Error(`Worker stopped with exit code ${code}`));
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});
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});
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};
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```
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```cjs
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'use strict';
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const {
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Worker, isMainThread, parentPort, workerData,
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Worker,
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isMainThread,
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parentPort,
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workerData,
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} = require('node:worker_threads');
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if (isMainThread) {
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@ -84,7 +124,25 @@ of data passed to the spawning thread's `worker.setEnvironmentData()`.
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Every new `Worker` receives its own copy of the environment data
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automatically.
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```js
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```mjs
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import {
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Worker,
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isMainThread,
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setEnvironmentData,
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getEnvironmentData,
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} from 'node:worker_threads';
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if (isMainThread) {
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setEnvironmentData('Hello', 'World!');
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const worker = new Worker(new URL(import.meta.url));
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} else {
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console.log(getEnvironmentData('Hello')); // Prints 'World!'.
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}
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```
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```cjs
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'use strict';
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const {
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Worker,
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isMainThread,
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@ -116,12 +174,6 @@ Is `true` if this code is running inside of an internal [`Worker`][] thread (e.g
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node --experimental-loader ./loader.js main.js
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```
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```cjs
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// loader.js
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const { isInternalThread } = require('node:worker_threads');
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console.log(isInternalThread); // true
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```
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```mjs
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// loader.js
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import { isInternalThread } from 'node:worker_threads';
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@ -129,14 +181,24 @@ console.log(isInternalThread); // true
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```
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```cjs
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// main.js
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// loader.js
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'use strict';
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const { isInternalThread } = require('node:worker_threads');
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console.log(isInternalThread); // true
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```
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```mjs
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// main.js
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import { isInternalThread } from 'node:worker_threads';
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console.log(isInternalThread); // false
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```
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```mjs
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```cjs
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// main.js
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import { isInternalThread } from 'node:worker_threads';
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'use strict';
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const { isInternalThread } = require('node:worker_threads');
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console.log(isInternalThread); // false
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```
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@ -150,7 +212,21 @@ added: v10.5.0
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Is `true` if this code is not running inside of a [`Worker`][] thread.
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```js
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```mjs
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import { Worker, isMainThread } from 'node:worker_threads';
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if (isMainThread) {
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// This re-loads the current file inside a Worker instance.
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new Worker(new URL(import.meta.url));
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} else {
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console.log('Inside Worker!');
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console.log(isMainThread); // Prints 'false'.
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}
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```
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```cjs
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'use strict';
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const { Worker, isMainThread } = require('node:worker_threads');
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if (isMainThread) {
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@ -183,7 +259,35 @@ For example, Node.js marks the `ArrayBuffer`s it uses for its
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This operation cannot be undone.
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```js
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```mjs
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import { MessageChannel, markAsUntransferable } from 'node:worker_threads';
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const pooledBuffer = new ArrayBuffer(8);
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const typedArray1 = new Uint8Array(pooledBuffer);
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const typedArray2 = new Float64Array(pooledBuffer);
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markAsUntransferable(pooledBuffer);
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const { port1 } = new MessageChannel();
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try {
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// This will throw an error, because pooledBuffer is not transferable.
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port1.postMessage(typedArray1, [ typedArray1.buffer ]);
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} catch (error) {
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// error.name === 'DataCloneError'
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}
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// The following line prints the contents of typedArray1 -- it still owns
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// its memory and has not been transferred. Without
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// `markAsUntransferable()`, this would print an empty Uint8Array and the
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// postMessage call would have succeeded.
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// typedArray2 is intact as well.
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console.log(typedArray1);
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console.log(typedArray2);
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```
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```cjs
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'use strict';
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const { MessageChannel, markAsUntransferable } = require('node:worker_threads');
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const pooledBuffer = new ArrayBuffer(8);
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@ -223,7 +327,18 @@ added: v21.0.0
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Check if an object is marked as not transferable with
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[`markAsUntransferable()`][].
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```js
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```mjs
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import { markAsUntransferable, isMarkedAsUntransferable } from 'node:worker_threads';
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const pooledBuffer = new ArrayBuffer(8);
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markAsUntransferable(pooledBuffer);
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isMarkedAsUntransferable(pooledBuffer); // Returns true.
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```
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```cjs
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'use strict';
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const { markAsUntransferable, isMarkedAsUntransferable } = require('node:worker_threads');
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const pooledBuffer = new ArrayBuffer(8);
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@ -252,7 +367,23 @@ This has no effect on `ArrayBuffer`, or any `Buffer` like objects.
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This operation cannot be undone.
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```js
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```mjs
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import { markAsUncloneable } from 'node:worker_threads';
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const anyObject = { foo: 'bar' };
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markAsUncloneable(anyObject);
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const { port1 } = new MessageChannel();
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try {
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// This will throw an error, because anyObject is not cloneable.
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port1.postMessage(anyObject);
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} catch (error) {
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// error.name === 'DataCloneError'
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}
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```
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```cjs
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'use strict';
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const { markAsUncloneable } = require('node:worker_threads');
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const anyObject = { foo: 'bar' };
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@ -309,7 +440,26 @@ using `worker.on('message')`, and messages sent from the parent thread
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using `worker.postMessage()` are available in this thread using
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`parentPort.on('message')`.
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```js
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```mjs
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import { Worker, isMainThread, parentPort } from 'node:worker_threads';
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if (isMainThread) {
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const worker = new Worker(new URL(import.meta.url));
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worker.once('message', (message) => {
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console.log(message); // Prints 'Hello, world!'.
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});
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worker.postMessage('Hello, world!');
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} else {
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// When a message from the parent thread is received, send it back:
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parentPort.once('message', (message) => {
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parentPort.postMessage(message);
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});
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}
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```
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```cjs
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'use strict';
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const { Worker, isMainThread, parentPort } = require('node:worker_threads');
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if (isMainThread) {
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@ -365,7 +515,6 @@ The example below shows the use of of `postMessageToThread`: it creates 10 neste
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the last one will try to communicate with the main thread.
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```mjs
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import { fileURLToPath } from 'node:url';
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import process from 'node:process';
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import {
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postMessageToThread,
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@ -378,7 +527,7 @@ const channel = new BroadcastChannel('sync');
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const level = workerData?.level ?? 0;
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if (level < 10) {
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const worker = new Worker(fileURLToPath(import.meta.url), {
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const worker = new Worker(new URL(import.meta.url), {
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workerData: { level: level + 1 },
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});
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}
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@ -402,6 +551,9 @@ channel.onmessage = channel.close;
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```
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```cjs
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'use strict';
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const process = require('node:process');
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const {
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postMessageToThread,
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threadId,
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@ -455,7 +607,20 @@ Receive a single message from a given `MessagePort`. If no message is available,
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that contains the message payload, corresponding to the oldest message in the
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`MessagePort`'s queue.
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```js
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```mjs
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import { MessageChannel, receiveMessageOnPort } from 'node:worker_threads';
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const { port1, port2 } = new MessageChannel();
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port1.postMessage({ hello: 'world' });
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console.log(receiveMessageOnPort(port2));
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// Prints: { message: { hello: 'world' } }
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console.log(receiveMessageOnPort(port2));
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// Prints: undefined
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```
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```cjs
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'use strict';
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const { MessageChannel, receiveMessageOnPort } = require('node:worker_threads');
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const { port1, port2 } = new MessageChannel();
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port1.postMessage({ hello: 'world' });
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@ -501,7 +666,18 @@ A special value that can be passed as the `env` option of the [`Worker`][]
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constructor, to indicate that the current thread and the Worker thread should
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share read and write access to the same set of environment variables.
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```js
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```mjs
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import process from 'node:process';
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import { Worker, SHARE_ENV } from 'node:worker_threads';
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new Worker('process.env.SET_IN_WORKER = "foo"', { eval: true, env: SHARE_ENV })
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.on('exit', () => {
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console.log(process.env.SET_IN_WORKER); // Prints 'foo'.
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});
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```
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```cjs
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'use strict';
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const { Worker, SHARE_ENV } = require('node:worker_threads');
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new Worker('process.env.SET_IN_WORKER = "foo"', { eval: true, env: SHARE_ENV })
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.on('exit', () => {
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@ -557,7 +733,19 @@ to this thread's `Worker` constructor.
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The data is cloned as if using [`postMessage()`][`port.postMessage()`],
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according to the [HTML structured clone algorithm][].
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```js
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```mjs
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import { Worker, isMainThread, workerData } from 'node:worker_threads';
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if (isMainThread) {
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const worker = new Worker(new URL(import.meta.url), { workerData: 'Hello, world!' });
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} else {
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console.log(workerData); // Prints 'Hello, world!'.
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}
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```
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```cjs
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'use strict';
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const { Worker, isMainThread, workerData } = require('node:worker_threads');
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if (isMainThread) {
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@ -580,7 +768,30 @@ changes:
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Instances of `BroadcastChannel` allow asynchronous one-to-many communication
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with all other `BroadcastChannel` instances bound to the same channel name.
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```js
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```mjs
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import {
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isMainThread,
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BroadcastChannel,
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Worker,
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} from 'node:worker_threads';
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const bc = new BroadcastChannel('hello');
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if (isMainThread) {
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let c = 0;
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bc.onmessage = (event) => {
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console.log(event.data);
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if (++c === 10) bc.close();
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};
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for (let n = 0; n < 10; n++)
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new Worker(new URL(import.meta.url));
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} else {
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bc.postMessage('hello from every worker');
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bc.close();
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}
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```
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```cjs
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'use strict';
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const {
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@ -681,7 +892,18 @@ The `MessageChannel` has no methods of its own. `new MessageChannel()`
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yields an object with `port1` and `port2` properties, which refer to linked
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[`MessagePort`][] instances.
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```js
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```mjs
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import { MessageChannel } from 'node:worker_threads';
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const { port1, port2 } = new MessageChannel();
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port1.on('message', (message) => console.log('received', message));
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port2.postMessage({ foo: 'bar' });
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// Prints: received { foo: 'bar' } from the `port1.on('message')` listener
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```
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```cjs
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'use strict';
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const { MessageChannel } = require('node:worker_threads');
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const { port1, port2 } = new MessageChannel();
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@ -720,7 +942,23 @@ added: v10.5.0
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The `'close'` event is emitted once either side of the channel has been
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disconnected.
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```js
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```mjs
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import { MessageChannel } from 'node:worker_threads';
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const { port1, port2 } = new MessageChannel();
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// Prints:
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// foobar
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// closed!
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port2.on('message', (message) => console.log(message));
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port2.on('close', () => console.log('closed!'));
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port1.postMessage('foobar');
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port1.close();
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```
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```cjs
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'use strict';
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const { MessageChannel } = require('node:worker_threads');
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const { port1, port2 } = new MessageChannel();
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@ -841,7 +1079,21 @@ In particular, the significant differences to `JSON` are:
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* {net.SocketAddress}es,
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* {X509Certificate}s.
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```js
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```mjs
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import { MessageChannel } from 'node:worker_threads';
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const { port1, port2 } = new MessageChannel();
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port1.on('message', (message) => console.log(message));
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const circularData = {};
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circularData.foo = circularData;
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// Prints: { foo: [Circular] }
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port2.postMessage(circularData);
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```
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```cjs
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'use strict';
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const { MessageChannel } = require('node:worker_threads');
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const { port1, port2 } = new MessageChannel();
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@ -866,7 +1118,33 @@ from either thread. They cannot be listed in `transferList`.
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`value` may still contain `ArrayBuffer` instances that are not in
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`transferList`; in that case, the underlying memory is copied rather than moved.
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```js
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```mjs
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import { MessageChannel } from 'node:worker_threads';
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const { port1, port2 } = new MessageChannel();
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port1.on('message', (message) => console.log(message));
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const uint8Array = new Uint8Array([ 1, 2, 3, 4 ]);
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// This posts a copy of `uint8Array`:
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port2.postMessage(uint8Array);
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// This does not copy data, but renders `uint8Array` unusable:
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port2.postMessage(uint8Array, [ uint8Array.buffer ]);
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// The memory for the `sharedUint8Array` is accessible from both the
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// original and the copy received by `.on('message')`:
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const sharedUint8Array = new Uint8Array(new SharedArrayBuffer(4));
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port2.postMessage(sharedUint8Array);
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// This transfers a freshly created message port to the receiver.
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// This can be used, for example, to create communication channels between
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// multiple `Worker` threads that are children of the same parent thread.
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const otherChannel = new MessageChannel();
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port2.postMessage({ port: otherChannel.port1 }, [ otherChannel.port1 ]);
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```
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```cjs
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'use strict';
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|
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const { MessageChannel } = require('node:worker_threads');
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const { port1, port2 } = new MessageChannel();
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|
|
@ -1105,7 +1383,30 @@ See [`port.postMessage()`][] for more information on how messages are passed,
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and what kind of JavaScript values can be successfully transported through
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the thread barrier.
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```js
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```mjs
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import assert from 'node:assert';
|
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import {
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Worker, MessageChannel, MessagePort, isMainThread, parentPort,
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} from 'node:worker_threads';
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if (isMainThread) {
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const worker = new Worker(new URL(import.meta.url));
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const subChannel = new MessageChannel();
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worker.postMessage({ hereIsYourPort: subChannel.port1 }, [subChannel.port1]);
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subChannel.port2.on('message', (value) => {
|
||||
console.log('received:', value);
|
||||
});
|
||||
} else {
|
||||
parentPort.once('message', (value) => {
|
||||
assert(value.hereIsYourPort instanceof MessagePort);
|
||||
value.hereIsYourPort.postMessage('the worker is sending this');
|
||||
value.hereIsYourPort.close();
|
||||
});
|
||||
}
|
||||
```
|
||||
|
||||
```cjs
|
||||
'use strict';
|
||||
|
||||
const assert = require('node:assert');
|
||||
const {
|
||||
Worker, MessageChannel, MessagePort, isMainThread, parentPort,
|
||||
|
|
@ -1391,7 +1692,29 @@ stuck in bootstrap. The following examples shows how the worker's entire
|
|||
lifetime never accumulates any `idle` time, but is still be able to process
|
||||
messages.
|
||||
|
||||
```js
|
||||
```mjs
|
||||
import { Worker, isMainThread, parentPort } from 'node:worker_threads';
|
||||
|
||||
if (isMainThread) {
|
||||
const worker = new Worker(new URL(import.meta.url));
|
||||
setInterval(() => {
|
||||
worker.postMessage('hi');
|
||||
console.log(worker.performance.eventLoopUtilization());
|
||||
}, 100).unref();
|
||||
} else {
|
||||
parentPort.on('message', () => console.log('msg')).unref();
|
||||
(function r(n) {
|
||||
if (--n < 0) return;
|
||||
const t = Date.now();
|
||||
while (Date.now() - t < 300);
|
||||
setImmediate(r, n);
|
||||
})(10);
|
||||
}
|
||||
```
|
||||
|
||||
```cjs
|
||||
'use strict';
|
||||
|
||||
const { Worker, isMainThread, parentPort } = require('node:worker_threads');
|
||||
|
||||
if (isMainThread) {
|
||||
|
|
@ -1400,9 +1723,7 @@ if (isMainThread) {
|
|||
worker.postMessage('hi');
|
||||
console.log(worker.performance.eventLoopUtilization());
|
||||
}, 100).unref();
|
||||
return;
|
||||
}
|
||||
|
||||
} else {
|
||||
parentPort.on('message', () => console.log('msg')).unref();
|
||||
(function r(n) {
|
||||
if (--n < 0) return;
|
||||
|
|
@ -1410,6 +1731,7 @@ parentPort.on('message', () => console.log('msg')).unref();
|
|||
while (Date.now() - t < 300);
|
||||
setImmediate(r, n);
|
||||
})(10);
|
||||
}
|
||||
```
|
||||
|
||||
The event loop utilization of a worker is available only after the [`'online'`
|
||||
|
|
|
|||
Loading…
Reference in New Issue