sewn

Sew threads of work together

Usage

Install sewn by running:

yarn add sewn

spawnThread(modulePath)

Spawn and communicate with a new thread

/* parent.mjs */

import { spawnThread } from 'sewn'

async function run() {
  const thread = spawnThread('./thread.mjs')

  thread.send({ id: 1, action: 'add', args: [1, 2] })
  thread.send({ id: 2, action: 'subtract', args: [2, 1] })
  thread.send({ id: 3, action: 'multiply', args: [3, 3] })
  thread.send({ id: 4, action: 'divide', args: [4, 2] })
  thread.end()

  for await (const { id, result } of thread) {
    console.log(id, result)
  }
}

run()

/* thread.mjs */

export default async function() {
  for await (const { id, action, args: [x, y] } of parent) {
    if (action === 'add') parent.send({ id, result: x + y })
    else if (action === 'subtract') parent.send({ id, result: x - y })
    else if (action === 'multiply') parent.send({ id, result: x * y })
    else if (action === 'divide') parent.send({ id, result: x / y })
  }
}

spawnThread takes the path to a module whose default export will be called from the new thread. A message channel facilitates communication between the main thread and the created thread; one side of the channel is returned by spawnThread, and the other side is passed into the module.

Each side is an async iterator from which messages can be consumed, via for await or the .next() method. Each side also has a .send() method for producing messages.

The object returned by spawnThread also has a .end() method that when called, closes the message queue, ends the async iterator, and allows the thread to exit. Messages already in the message channel will be processed before the channel closes.

spawnThreadPool(modulePath)

Spawn and communicate with a pool of threads.

Messages produced by the parent are consumed round-robin by each thread in the pool.

The interface is the same as spawnThread(modulePath).