Named Tasks

Piscina supports running named tasks within a single worker file. This example demonstrates how to use a dispatcher pattern to execute different operations based on the task name.

Javascript

index.js

'use strict';

const Piscina = require('piscina');
const { resolve } = require('path');
const { makeTask } = require('./helper');

const piscina = new Piscina({
  filename: resolve(__dirname, 'worker.js')
});

(async function () {
  const result = await Promise.all([
    piscina.run(makeTask('add', 4, 6)),
    piscina.run(makeTask('sub', 4, 6))
  ]);
  console.log(result);
})();

Typescript

index.ts

import Piscina from "piscina";
import { resolve } from "path";
import { filename } from "./worker";
import { makeTask } from "./helper";

const piscina = new Piscina({
  filename: resolve(__dirname, "./workerWrapper.js"),
  workerData: { fullpath: filename },
});
(async function () {
  const result = await Promise.all([
    piscina.run(makeTask('add', 4, 6)),
    piscina.run(makeTask('sub', 4, 6))
  ]);
  console.log(result);
})();

The worker file uses a dispatcher to handle different operations:

Javascript

worker.js

'use strict';

const { dispatcher } = require('./helper');

module.exports = dispatcher({
  add (a, b) { return a + b; },
  sub (a, b) { return a - b; }
});

Typescript

worker.ts

import { dispatcher } from './helper';

export default dispatcher({
  add (a: number, b: number): number { return a + b; },
  sub (a: number, b: number): number { return a - b; }
});

The helper file provides utility functions for creating tasks and dispatching them:

Javascript

helper.js

function makeTask (op, ...args) {
  return { op, args };
}

function dispatcher (obj) {
  return async ({ op, args }) => {
    return await obj[op](...args);
  };
}

module.exports = {
  dispatcher,
  makeTask
};

Typescript

helper.ts

type Task = {
  op: string;
  args: any[];
};

export function makeTask (op: string, ...args: any[]): Task {
  return { op, args };
}

export function dispatcher (obj: Record<string, Function>) {
  return async ({ op, args }: Task) => {
    return await obj[op](...args);
  };
}

You can also check out this example on github.