Node.js worker_threads Example

This example demonstrates using wasm-bindgen with Node.js worker_threads for multithreading, supporting both CommonJS and ESM targets.

Features Tested

1. Main thread auto-initialization - Backwards compatibility with existing code
2. Worker thread initialization - Using initSync({ module, memory })
3. Shared atomic counter - Verifies memory is actually shared between threads
4. Memory growth detection - Tests the byteLength fix for SharedArrayBuffer
5. Memory growth visibility - Tests that memory growth is visible across threads

Building

npm run build

Running

npm test

How It Works

When targeting Node.js (CJS or ESM) with threads enabled, wasm-bindgen generates:

• initSync(opts) - Initialize the WASM module synchronously
• __wbg_get_imports(memory) - Get the imports object with optional custom memory
• __wbg_wasm_module - The compiled WebAssembly.Module for sharing with workers
• __wbg_memory - The shared WebAssembly.Memory

Main thread auto-initializes on require() or import. Worker threads should call:

// CJS
const wasm = require('./pkg/nodejs_threads.js');
wasm.initSync({
    module: workerData.wasmModule,  // from main thread
    memory: workerData.memory       // from main thread
});

// ESM
import { initSync } from './pkg/nodejs_threads.js';
initSync({
    module: workerData.wasmModule,  // from main thread
    memory: workerData.memory       // from main thread
});

TypeScript Support

Full TypeScript declarations are generated for all exports:

import {
    initSync,
    __wbg_get_imports,
    __wbg_wasm_module,
    __wbg_memory,
    type InitSyncOptions
} from './pkg/nodejs_threads.js';