How would you architect a thread pool using Web Workers to process a large task queue efficiently?

Q: How would you architect a thread pool using Web Workers to process a large task queue efficiently?

class WorkerPool { constructor(workerScript, size) { this.workers = Array(size).fill().map(() => new Worker(workerScript)); this.taskQueue = []; this.idleWorkers = [...this.workers]; } runTask(data) { if (this.idleWorkers.length) { const worker = this.idleWorkers.pop(); worker.postMessage(data); return new Promise(resolve => worker.onmessage = (e) => { this.idleWorkers.push(worker); resolve(e.data); }); } else { return new Promise(resolve => this.taskQueue.push({ data, resolve })); } } }

Difficulty: 6/10

Web Workers, thread pool, task queue

Create a pool of workers, maintain a task queue, assign tasks to idle workers, and use `postMessage` for input/output. Handle worker errors and respawn if needed.

Worker pool pattern

Scenario Questions

0-2 years experience

1Suppose you need to offload image thumbnail generation to a Web Worker pool in a single‑page app. How would you set up the pool and assign each image task?
2If you have a queue of 50 small calculations and you create three Web Workers, what happens when a worker finishes its current job? How do you ensure the next task is processed?

2-5 years experience

Follow-up Questions

How would you detect and track when a worker becomes idle?
What metrics would you expose to monitor the pool in production?
How do you handle errors or crashes from a worker without losing pending tasks?

How would you architect a thread pool using Web Workers to process a large task queue efficiently?

Create a pool of workers, maintain a task queue, assign tasks to idle workers, and use postMessage for input/output. Handle worker errors and respawn if needed.

Scenario Questions

Follow-up Questions

How would you architect a thread pool using Web Workers to process a large task queue efficiently?

Create a pool of workers, maintain a task queue, assign tasks to idle workers, and use postMessage for input/output. Handle worker errors and respawn if needed.

Scenario Questions

Follow-up Questions

Create a pool of workers, maintain a task queue, assign tasks to idle workers, and use `postMessage` for input/output. Handle worker errors and respawn if needed.

Create a pool of workers, maintain a task queue, assign tasks to idle workers, and use `postMessage` for input/output. Handle worker errors and respawn if needed.