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Tinypool - the node.js worker pool 🧡

Piscina: A fast, efficient Node.js Worker Thread Pool implementation

Tinypool is a fork of piscina. What we try to achieve in this library, is to eliminate some dependencies and features that our target users don't need (currently, our main user will be Vitest). Tinypool's install size (38KB) can then be smaller than Piscina's install size (6MB). If you need features like utilization or NAPI, Piscina is a better choice for you. We think that Piscina is an amazing library, and we may try to upstream some of the dependencies optimization in this fork.

  • βœ… Smaller install size, 38KB

  • βœ… Minimal

  • βœ… No dependencies

  • βœ… Physical cores instead of Logical cores with physical-cpu-count

  • ❌ No utilization

  • ❌ No NAPI

  • Written in TypeScript, and ESM support only. For Node.js 14.x and higher.

In case you need more tiny libraries like tinypool or tinyspy, please consider submitting an RFC


In main.js:

import path from 'path'
import Tinypool from 'tinypool'

const pool = new Tinypool({
  filename: new URL('./worker.js', import.meta.url).href,

;(async function () {
  const result = await{ a: 4, b: 6 })
  console.log(result) // Prints 10

In worker.js:

export default ({ a, b }) => {
  return a + b


We have a similar API to Piscina, so for more information, you can read Piscina's detailed documentation and apply the same techniques here.

Additional Options
  • isolateWorkers: Default to false. Always starts with a fresh worker when running tasks to isolate the environment.
  • workerId: Each worker now has an id ( <= maxThreads) that can be imported from tinypool in the worker itself (or process.__tinypool_state__.workerId)


The Vitest team for giving me the chance of creating and maintaing this project for vitest.

Piscina, because Tinypool is not more than a friendly fork of piscina.


🧡 A minimal and tiny Node.js Worker Thread Pool implementation, a fork of piscina, with fewer features and smaller size (38KB)




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