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.

• ✅ Smaller install size, 38KB

• ✅ Minimal

• ✅ No dependencies

• ✅ 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

Example

In main.js:

import Tinypool from 'tinypool'

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

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

In worker.js:

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

API

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

Tinypool specific APIs

Pool constructor options

• isolateWorkers: Default to false. Always starts with a fresh worker when running tasks to isolate the environment.
• terminateTimeout: Defaults to null. If terminating a worker takes terminateTimeout amount of milliseconds to execute, an error is raised.

Pool methods

• cancelPendingTasks(): Gracefully cancels all pending tasks without stopping or interfering with on-going tasks. This method is useful when your tasks may have side effects and should not be terminated forcefully during task execution. If your tasks don't have any side effects you may want to use { signal } option for forcefully terminating all tasks, including the on-going ones, instead.

Exports

• workerId: Each worker now has an id ( <= maxThreads) that can be imported from tinypool in the worker itself (or process.__tinypool_state__.workerId).

Authors

Mohammad Bagher

Sponsors

Your sponsorship can make a huge difference in continuing our work in open source!

Credits

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.