bun-workers

Bun Workers

Bun supports Web Workers and Node.js worker_threads for parallel execution.

Web Workers

Basic Usage

// main.ts
const worker = new Worker(new URL("./worker.ts", import.meta.url));

worker.postMessage({ type: "start", data: [1, 2, 3, 4, 5] });

worker.onmessage = (event) => {
  console.log("Result:", event.data);
};

worker.onerror = (error) => {
  console.error("Worker error:", error.message);
};

// worker.ts
self.onmessage = (event) => {
  const { type, data } = event.data;

  if (type === "start") {
    const result = data.map((x) => x * 2);
    self.postMessage(result);
  }
};

Worker with URL

// Import from file path
const worker = new Worker(new URL("./worker.ts", import.meta.url));

// Or with blob URL
const code = `
  self.onmessage = (e) => {
    self.postMessage(e.data * 2);
  };
`;
const blob = new Blob([code], { type: "application/javascript" });
const worker = new Worker(URL.createObjectURL(blob));

Transferable Objects

// main.ts
const buffer = new ArrayBuffer(1024 * 1024); // 1MB
const view = new Uint8Array(buffer);
view.fill(42);

// Transfer ownership (zero-copy)
worker.postMessage({ buffer }, [buffer]);
// buffer is now detached (empty)

// worker.ts
self.onmessage = (event) => {
  const { buffer } = event.data;
  const view = new Uint8Array(buffer);
  // Process buffer...

  // Transfer back
  self.postMessage({ buffer }, [buffer]);
};

Shared Memory

// main.ts
const shared = new SharedArrayBuffer(1024);
const view = new Int32Array(shared);

worker.postMessage({ shared });

// Both main and worker can access
Atomics.add(view, 0, 1);

// worker.ts
self.onmessage = (event) => {
  const { shared } = event.data;
  const view = new Int32Array(shared);

  // Atomic operations for thread safety
  Atomics.add(view, 0, 1);
  Atomics.notify(view, 0);
};

Node.js worker_threads

// main.ts
import { Worker, isMainThread, parentPort, workerData } from "worker_threads";

if (isMainThread) {
  const worker = new Worker(import.meta.filename, {
    workerData: { numbers: [1, 2, 3, 4, 5] },
  });

  worker.on("message", (result) => {
    console.log("Result:", result);
  });

  worker.on("error", (err) => {
    console.error("Error:", err);
  });

  worker.on("exit", (code) => {
    console.log("Worker exited with code:", code);
  });
} else {
  // Worker code
  const { numbers } = workerData;
  const sum = numbers.reduce((a, b) => a + b, 0);
  parentPort?.postMessage(sum);
}